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Landsat 8 normally images all Earth landmasses every 16 days. However, at high latitudes, there is considerable overlap because Landsat 8’s orbital tracks converge at the Poles. As a result, this increases the temporal frequency of Landsat 8 coverage over northern Greenland.

Building on this imaging overlap, Landsat 8 takes advantage of long hours of daylight in the Arctic to acquire “nighttime” sunlit images, increasing temporal coverage even more. The two Landsat 8 images were acquired a little over 3 hours apart, one on its descending orbit and one ascending. Having multiple images increases the chances of acquiring more cloud-free images and helps scientists monitor iceberg calving events.

Scientists observed rifts in Petermann Glacier throughout the first decade of the 2000s. The rift that caused the 2010 break was first spotted in satellite imagery in 2001. See below for the location of this rift in a 2001 Landsat image.

The massive calving event in 2010 removed 28 kilometers of the ice shelf. The result was an ice island four times the size of Manhattan, about 270 square kilometers. It was the largest iceberg to form in the Arctic since 1962.

The last image displayed in this section shows a size comparison of Manhattan Island (yellow outline) to the iceberg.

(Black stripes run through the images because of the Scan Line Corrector failure on Landsat 7 in May 2003.)

Just two years later, another large iceberg broke off Petermann Glacier. This one was estimated at 130 square kilometers—about half the size of the 2010 iceberg. But this calving broke off the glacier tongue farther upstream and moved the front end of the glacier farther inland than has been observed since 1876, the first reported measurements of the glacier.

The floating ends of glaciers like Petermann are known as ice shelves. They act as doorstops. When these ice shelves suddenly splinter and weaken, the glaciers that feed them speed up. The result is more ice flowing into the ocean, which could raise global sea levels.

The development of these icebergs is a natural process; however, when there are two major breaks in two years, scientists must take notice. Even large breaks do not amount to a collapse of the floating extension; nevertheless, they are important events.

(Black stripes run through the images because of the Scan Line Corrector failure on Landsat 7 in May 2003.)

A new rift formed on Petermann Glacier in 2017. An older crack to the right of the new rift also extends toward the glacier’s center. By 2020, this new rift had met up with the older crack. If an iceberg breaks off, it would be Petermann’s third massive iceberg calving since 2010. It also could place the new calving face much farther upstream than the 2010 break.

Close-up images from Sentinel-2 take advantage of its 10-meter spatial resolution to show the new rift in greater detail. Landsat 8 and Sentinel-2 complement each other by imaging glacial movement and possible calving events.

The prominent vertical line could be from deformation of the ice as it flows over the bedrock farther upstream. The irregular topographic surface of the underlying bedrock could have caused the ice to develop this longitudinal crevasse as it moved over bedrock, resulting in a line being drawn the length of the glacier as it flows. Besides the new rift, other bumps and lines extend from this longitudinal line, which are stress fractures from the glacial movement.

Along with becoming longer, notice that the rifts are also moving downstream between 2017 and 2022 as the glacier flows.

On April 30, 2018, rapid changes in the East Rift Zone were detected. The Pu‘u ‘Ō‘ō crater floor collapsed. Ground deformation toward the east indicated magma intrusion approaching the Leilani Estates neighborhood, 20 km from Pu‘u ‘Ō‘ō.

Based on numerous geological, geochemical, and geophysical instruments, the USGS Hawaiian Volcano Observatory and other scientists determined that magma had drained from below Pu‘u ‘Ō‘ō crater. It then intruded through underground tunnels and emerged at eruptive vents, or fissures, in the lower East Rift Zone.

On May 3, the first of 24 fissures along a 6-km line opened within Leilani Estates. Fissure 8 became the dominant vent on May 28. It shot lava tens of meters into the air and sent a vigorous flow toward the coast, ultimately entering the ocean near the eastern tip of the island.

This series of images shows the progression of the lava flows throughout the summer of 2018. Clouds often obscure views of the island, but numerous observations from Landsat, Sentinel-2, and Resourcesat offered peeks through the clouds to the location of fresh lava. Some of the images also show “laze.” When lava mixes with seawater, it creates a noxious gas plume that looks like clouds or smoke. The word is a blend of the words lava and haze. Laze can cause skin and eye irritation and breathing difficulties.

This flow ended abruptly on August 4, 2018. By this time, lava had destroyed more than 700 structures, covered 13.7 square miles (35.5 km²) of land, and added about 741 acres (300 hectares) of land to the island. Lava was a couple hundred meters thick in some places.

A wet 2018–2019 winter caused extra plant growth on Maui, and thus extra fuel, and was followed by drought and record-breaking heat in summer 2019. That set up conditions for an intense fire season. Firefighters reported the unusual weather conditions that made the fires worse: above normal temperatures and below normal humidity.

In summer 2019, at least 19,300 acres burned across Maui, nearly all of it in the former cane fields. The dry grasses that largely replaced the cane fields are especially vulnerable to fire. Notice that the fire scar visible in the July 27, 2019, image didn’t last long, evidence that, unlike a forest fire burn scar, nonnative grass recovers rapidly and outcompetes native grasses after a fire.

Taking a closer look at Garden City shows the expansion in area the city experienced since 1972. They also show the proximity of the city to those center-pivot irrigation circles. Four of these circles take up almost 1 square mile, or one section, of land.

Southwest of Garden City is an area absent of irrigated crops. This marks the location of the Sandsage Bison Range Wildlife Area, a reserve for many Plains natives, including an American bison herd.

Another gap in irrigated cropland is a bit to the west of the game refuge. Marked by light spots is Holcomb Station, a coal-fired power plant operated by the Sunflower Electric Power Corporation. The plant opened in 1983, so it does not appear in the 1972 Landsat image. The 362-megawatt station uses coal mined in Wyoming's Powder River Basin.

The coastal wetlands of Senegal are centered on the Saloum River and a myriad of estuaries and tidal flats that make up this complex ecosystem. The estuaries are generally bordered by dense, vigorous stands of mangroves (dark red tones in the Landsat images). Part of this ecosystem is protected in Saloum Delta National Park. The wetlands are critical habitats for wintering Palearctic birds, as well as many species of fish and mollusks.

The mangrove vegetation is made up of several species. Some mangrove species form low canopies, but others of the Rhizophora genus are among the tallest in the world, attaining heights of up to 40 meters. Mangroves grow in habitats that are periodically flooded by seawater (tidal influence) and river water. They are halophytes, plants that grow in salty environments.

Since the late 1960s, it has become apparent that many of the mangrove forests are dying. One theory is that there is a serious mangrove disease that is systematically wiping them out. However, most evidence indicates that the mangrove die-off is related to the widespread Sahelian drought, which has plagued the region since 1968. The lack of rainfall has led to an accumulation of salts, exceeding the tolerance levels of the mangroves.

The die-off is particularly acute in the northern half of the Saloum River wetland complex (note the change in tone on the Landsat imagery, from dark red to dark gray). Today, there are vast areas of standing dead mangrove carcasses; many of these areas have been reduced to barren mud flats. The southern reaches of the wetland complex, however, still has healthy stands of mangrove forests.

The Cheyenne Bottoms are on the North American Central Flyway, kind of a bird highway for migration. The vast, diverse marsh provides food and water for a multitude of migrating bird species during both spring and fall migrations. Most of Kansas is too dry for such a stopover, and reservoirs are too deep. Birds need shallow water and long shorelines.

Summer 2022 had below normal precipitation statewide and above normal temperatures. No water was available from Wet Walnut Creek to divert into the Bottoms. By November 2022, the U.S. Drought Monitor showed that a third of Kansas was in exceptional drought. Landsat images from October 2021 and October 2022 show that birds had nothing to stop for in fall 2022.

Floods are examples of short-term environmental change. They cause substantial damage and change for only a short time, such as a couple of weeks. The damage done to crops can last for an entire growing season, but in most cases, the landscape goes back to normal after the floodwaters recede. In some cases, however, a flood can cause more lasting change.

This flood changed the course of the Wabash River just above where it flows into the Ohio River. We have to go to a different Landsat image to see this happen, the one just south of the scene we’ve been examining. Images show a new cutoff that was formed from this flooding. About 2,200 acres of the land was rendered inaccessible by the new cutoff and shortened the river by about 7.5 miles.

The Landsat images that are shown on Earthshots are combinations of three different wavelengths of the electromagnetic spectrum. Typically, the images show a combination of visible and infrared light; therefore, they are false color images. When these wavelengths, or bands, are shown individually instead of combined, different details sometimes emerge.

In the case of this Selkirk Karman vortex street scene, Landsat 7’s band 5 hints at a feature not visible in the image featured in the first section, which is a combination of bands 5, 4, and 3. Do you see it? Band 7 shows it even better. Northeast of the island, just east of the vortices, there is a bright spot and a bright plume trailing from it to the northeast. This may be a westbound ship, the effect of the ship’s exhaust shown in the clouds.

It soon became too dark to see A-74, which covered 1,270 km², as the Antarctic winter set in. But Landsat 8 continued imaging with its Thermal Infrared Sensor (TIRS). The imagery is visibly dark, but TIRS detects temperature on the surface.

TIRS shows relatively cooler temperatures darker than warmer temperatures, so the iceberg and ice shelf appear black. Clouds are relatively warmer than ice, so clouds sometimes cover the ice with swaths of gray.

TIRS reveals what could not be seen in the darkness. The iceberg separates from the ice shelf, moves away, then bumps back into it before drifting south. In August 2021, in a timeframe of less than 2 weeks, the berg spun around the tip of Brunt Ice Shelf, brushed past it, rotated counterclockwise, and continued south. Landsat 8 spotted it with its visible bands in February 2022 much farther south along the Antarctic coast.

It’s unknown exactly how the ice shelf will respond to the 2021 North Rift calving. The situation is being monitored closely by Landsat along with Sentinel, WorldView, ground-penetrating radar, drone imagery, and a network of GPS stations.

Another iceberg broke off the Brunt Ice Shelf during the dark Antarctic winter in May 2024. Landsat’s Thermal Infrared Sensor (TIRS) instrument can spot icebergs in the dark, allowing scientists to see the new break even in the dark of winter. Landsat’s expanded acquisition program called LEAP—Landsat Extended Acquisitions of the Poles—provides even more observations of ice shelves in polar regions. 

The iceberg, named A-83, is about the size of Portland, Oregon. It broke from an area that had previously formed a rift called Halloween Crack. The Landsat series displayed here shows imagery from TIRS.  Darker areas are relatively colder than bright areas.

The iceberg is already moving, and Landsat’s TIRS instrument will be able to track it throughout the Antarctic winter because of the LEAP imaging plan. The new iceberg reinforces that while calving is normal, the recent rash of iceberg calvings at Brunt may mean that the ice shelf is destabilizing.

Near the common borders of Ukraine, Belarus, and Russia, the Chernobyl Nuclear Power Plant lies near the Pripyat River at the northwestern end of a cooling pond. The pond is 12 km long; during normal operation the plant discharged warm water counterclockwise around the pond, taking in cool water near the north end. Just northwest of the plant is the city of Pripyat. The smaller town of Chernobyl lies south of the cooling pond.

The 1986 and 1992 images clearly show farm abandonment. Agriculture appears as a collage of bright green (growing crops) and tan (highly reflective bare ground). Many of these areas appear a flat gray-green in 1992, indicating natural vegetation that has taken over the abandoned fields. The later images show that this land change persists.

While the reactor was still on fire, all settlements within 30 km were evacuated, including Pripyat (1986 population 45,000), Chernobyl (1986 population 12,000), and 94 other villages (estimated total population 40,000). This area remains almost completely abandoned and is called the Chernobyl exclusion zone. The area is a mixture of former agriculture, forest, and marshland. It has been mostly free from human intervention since 1986.

Radiation contamination later forced abandonment even outside the 30-km zone. High levels of cesium-137 detected years later caused further abandonment. In all, more than 120,000 people from 213 villages and cities were relocated outside contaminated areas.

In 2011, the director of the Chernobyl power plant, Ihor Gramotkin, was asked when the area would again be inhabitable. He responded, “At least 20,000 years” (Harrell and Marson).

All of the water that keeps the Mesopotamian Marshes alive comes from the Tigris and Euphrates rivers. Those rivers originate from precipitation in the Anatolian highlands of Turkey and the Zagros highlands of Iran, which occurs mostly in winter as snow. The snowmelt then provides—historically, at least—a flooding pulse downstream every spring. The land flattens out in southern Iraq, where the rivers slow and drop sediment, meander, and split into branches before flowing into the Persian Gulf.

The Mesopotamian marshlands absorb the excess water and expand in the spring, then shrink in the summer. That’s the normal seasonal pattern.

In the 1960s, the estimated spring extent of the marshes was 15,000–20,000 square kilometers. The vast marshland is vulnerable to drought and international conflict.

Large-scale draining of the marshes began in earnest after the Gulf War of 1991. Water from the Tigris and Euphrates rivers was redirected to bypass the marshes. A west-east canal, 40 kilometers long and 1–2 kilometers wide, connected to the north-south Prosperity River, the prominent canal in the middle of these images. Even wider than the west-east canal, the Prosperity River is basically a massive moat that captures water from the rivers and tributaries and prevents it from flowing into the marshes.

Throughout the 1990s, the marshes declined dramatically. The loss of vegetation and water is widespread and clear to see in the images. The extent of the marshland was reduced by about 85% by 2000.

The fertile muck soils along the south shore of Lake Okeechobee in the Everglades Agricultural Area are intensively farmed. Tomatoes, beans, squash, peppers, and other crops are grown during the winter and shipped north. Sugarcane is the main crop there from spring through the fall.

The bottom center of the later images reveals the location of Stormwater Treatment Area (STA) 3/4, one of six STAs mandated by the State of Florida’s Everglades Forever Act, passed in 1994. STA 3/4 is distinct from the polygons of the agricultural area. Just to its west is Holey Land Wildlife Management Area.

These constructed wetlands are designed to remove phosphorus that comes from agricultural runoff. Under previous agricultural practices, phosphorus from fertilizers was allowed to run off into the Everglades. Phosphorus is an essential nutrient, but too much of it alters the Everglades’ natural habitats.

These treatment areas channel runoff through shallow marshes filled with plants that absorb phosphorus, reducing the amount that flows into the Everglades. The plants include cattail, southern naiad, hydrilla, and algae. These plants continue to absorb phosphorus even after they die and decompose. The underlying limestone layer then holds the phosphorus, providing long-term storage.

Besides helping to restore the Everglades, these treatment areas have become a great home for wading birds, ducks, and alligators. Florida offers hunting and other recreational opportunities at many of these treatment areas.

Irrigated agriculture in the valley, shown by the red field patterns, has increased. This agriculture depends on rainfall captured in the mountains and channeled to the valley floor, as well as nearby rivers and drilled wells.

The area of vegetation just outside the Nile River Delta northwest of Cairo, Egypt, is new agricultural development, with some of the crops irrigated through center-pivot irrigation. In these Landsat images, red indicates vegetation. 

The most common crops grown are cotton, rice, corn, potatoes, oranges, and wheat. Although areas at a distance from the Nile often are not able to be irrigated, land that does support crops produces high yields and is harvested two or three times in many years.

Food shortages have been documented for thousands of years in Egypt, and they can still cause problems. As the Egyptian population grows, producing enough food has become more difficult, so the government subsidizes food to make comfortable life possible. One staple food highly subsidized in Egypt is bread. The "bread riots" in 1977 and 2008 were the result of a reduction in those subsidies.

Despite government regulation that keeps the production of non-food crops like cotton low, Egypt still imports much of its food, especially wheat. This can increase the price of food even higher.

Dams being built on the Nile River and its tributaries upstream from Egypt could affect the amount of water making its way to Egypt.

Southeast of Riyadh, irrigation has clearly increased over time, particularly around the city of Al Kharj. The red circles are fields with center-pivot irrigation systems, drawing water from Saudi Arabia’s aquifers. This irrigation development resulted from the investment of part of Saudi Arabia’s oil revenues in an effort to modernize agriculture.

One of the factors that improves on Landsat sensors over the project’s history is the quality of the data. For example, compare these images of glaciers in Alaska’s Chitina River Valley from 1980. There is more background noise in an RBV image than there is in the MSS image. The RBV on Landsat 3 had a slightly higher spatial resolution, but the low signal-to-noise ratio makes it harder to pull out surface detail.

The 2018 image from Landsat 8’s Operational Land Imager has even better signal-to-noise ratio and higher resolution than both early sensors. The image reveals more detail about the roughness and flow of the ice. Landsat 8’s shortwave infrared bands provide a better distinction between ice and rock or soil.

High-quality data is needed in studying glaciers. Glaciers reflect visible light and appear bright white in natural color satellite images. But a glacier absorbs near-infrared light. The near-infrared and shortwave infrared imaging on later Landsats show the difference between snow and bare ground more clearly.

However, glaciologists still found RBV useful for mapping arctic regions. In high latitudes, images acquired at low sun angles helped enhance local topographic relief. The high resolution of the RBV on Landsat 3 supplemented MSS imagery.

In the RBV image of the Chitina River Valley, the brightest wavy streaks are glaciers. Note that they extend farther downstream in 1980 than they do in 2018. In the Landsat 8 image, wavy blue streaks indicate glaciers. They are generally in the same location as in the 1980 image, just diminished.

While RBV might not be exactly what is needed or have the ideal attributes for a study or for mapping forests, glaciers, and other land covers, perhaps it’s one more tool to add to the collection in studying land change. It’s at least worth another look. Besides, as Faundeen said, “RBV is another interesting chapter in the Landsat story.”

Many of the world’s highest peaks are the barely tallest points of high ranges, but Kilimanjaro stands alone, 15,000 feet above the surrounding plains. It actually has three peaks from three old volcanoes: Kibo (2), Mawenzi , and Shira.

In these Landsat images, concentric rings show the vegetation zones around this unusual peak. The bare summit is surrounded by low grass and shrubs. These transition to a band of forest, protected as a reserve, which appears bright green. Below this is a densely populated agricultural area, appearing as speckled light green in the Landsat images. And at its base, the mountain turns dry again, supporting fewer plants and people.

People have farmed the lower slopes for at least 2,000 years. In the last century, the mountain’s population has grown rapidly—about tenfold between 1910 and 2000. These people raised cattle, fruits and vegetables, and coffee. Prevented from migrating upslope by the forest/wildlife preserve, people have moved out into drier areas.

Play this animation to see the change in this area happen from 1975 to 2017. The animation uses a Landsat image from most of the years in this time period to demonstrate the rapid rate of deforestation. Huge areas of Rondônia's dense rain forest transform to cleared areas in only a few decades. Unseen in these images are the effects of the deforestation on wildlife habitats and local and global climate.

The coal mines in the PRB advance quickly enough to see a lot of change from year to year. The animation here shows the annual change of the mines. Each image represents one year from 1984 to 2024.

Watch this animation of Landsat images, or view the individual images at your own speed below.

In the flooded season, this part of Mali’s landscape stands out as bright green against the arid brown African Sahel. The Niger River and the Inland Delta have been an important water supply in the southern Sahara for thousands of years.

The river channels, lakes, swamps, and floodplains provide the main livelihoods in the delta: livestock, fishing, and farming. The delta is also a refuge for many migrating birds. After rice farming and livestock, fishing is the most important industry of the delta. The catch varies from year to year depending on water levels. An overall decrease in available water in the delta directly affects the population in this industry.

This series of images shows that the extent of the seasonal flood can vary. For example, 1984 was a low flood year, and the green extent in the image is smaller than it is for 1999. Another low water year was 2011. Exceptionally high floods can damage habitats and irrigation, but extremely low flows like those in 1984 can be disastrous. The loss of livestock caused by the lack of water one year can have long-lasting effects.

Two main threats to the region are inadequate water management and climate change. With growing water use and a predicted decrease in rain in the Sahel, the river flow of the Niger is expected to decline. The livelihoods of the delta’s people could be at risk.

Diverting upstream water for irrigation means less water for the delta. For example, the Fomi Dam in Guinea is being planned. The two countries are working on assessing the possible risks and benefits of the dam.

(Black stripes run through the 2011 image because of the Scan Line Corrector failure on Landsat 7 in May 2003.)

Antelope Valley in southern California is the western part of the Mojave Desert. The San Gabriel Mountains and the Tehachapi Mountains give the valley a triangular shape. The southern edge of the valley is the San Andreas Fault.

While farming is going on in the valley in the more traditional sense, with irrigated fields showing up as bright green circles or rectangles in these Landsat images, farming of a different kind is also going on. With average annual wind speeds of 14 to 20 miles per hour and plenty of clear, sunny days, this part of the desert is on the cutting edge of wind and solar power.

(The small burn scar seen in the 2023 image is the Danny Fire, which burned almost 1,600 acres.)

Mangroves in the Ayeyarwady Delta are also being replaced by aquaculture. In the southwestern part of the delta, brackish shrimp pond development is expanding. The dark blue shapes in the images represent the shrimp ponds. Not as much land is being taken up by aquaculture, but this industry is growing.

While some mangroves have been restored on the delta, the aquaculture, agriculture, and cutting activities need to be monitored so that the benefits of mangroves can be maintained. Researchers continue to use Landsat and other remote sensing information to monitor this region.

We see a lot of change with 50 years of Landsat imagery, along with the declassified satellite imagery in the archives at EROS. The drying of the Aral Sea is likely the most dramatic change occurring over the past several decades in this imagery.

The Aral Sea once covered about 68,000 square kilometers, a little bigger than the U.S. state of West Virginia. It was the 4th largest lake in the world. It is now only about 10% of the size it was in 1960. Coastlines receded several kilometers from what were once coastal communities.

The Aral Sea is a terminal lake. Large permanent snow fields and glaciers in mountain ranges feed the two major rivers that flow into it, but it has no outlet. Syr Darya flows into the northern part of the Aral Sea. Amu Darya flows into the southern part. (Darya means river in the Turkic languages of central Asia.)

The precipitation rate over the Aral Sea is very low, less than 200 millimeters per year. However, 1,000–1,200 millimeters of water evaporates from the sea each year. Therefore, stability of the water level greatly depends on inflow from these two rivers, which has diminished over the past few decades leading to the shrinking of the lake.

The sea has in fact split into two separate bodies of water, referred to as the North Aral Sea and the South Aral Sea. The North Aral has stabilized but the South Aral has continued to shrink and become saltier. Up until the 1960s, Aral Sea salinity was around 10 grams per liter, less than one-third the salinity of the ocean. The salinity level now exceeds 100 grams per liter in the South Aral, which is about three times saltier than the ocean.

The effects of this dramatic change are far-reaching, geographically, environmentally, and economically. The subsequent sections describe how a body of water this size could nearly disappear so quickly.

The city of Aralsk is shown in the 1964 ARGON image on the coast of the sea. By 1977, the sea had retreated from the city but was still just a few kilometers away. As depicted in the 2015 image, Aralsk sits nearly 20 km from the water’s edge.

Commercial fishing in the Aral Sea peaked in the late 1950s. With the drop in water levels and rise in salinity, the fish that once thrived in the sea could not survive. As a result, commercial fishing was no longer sustainable by the early 1980s.

With the recovery of the North Aral, commercial fishing has started up again. It’s still just a fraction of what it was in the 1950s, but Aralsk is again processing fish at a new plant, established after the completion of the Kok-Aral Dam in 2005. Aralsk is not the thriving city it once was, but the return of the North Aral gives residents some hope of recovery.

The early images show main roads cutting through the forest. Highway 421 snakes through the forest south-southwest from the city of Ariquemes, and Highway 364 runs roughly north to south through Ariquemes. More roads branch out from the main ones to create the fishbone pattern. As time goes on, a patchwork of cleared areas, forest remnants, and settlements is left behind.

The bodies of water further south, east of Tampa, look completely different, because they have a much more human origin: phosphate mining.

South of Orlando lies the world's most productive source of phosphate, a critical nutrient for modern agriculture. In these images, plants look red and phosphate mines appear as a bright, high-contrast mix of white bare earth and blue-black ponds. The images show the phosphate region expanding, as more lands were put through the cycle of mining and reclamation.

Under just the right conditions, some ocean sediments (like those forming limestone) become rich in phosphorus. Ideally, an upwelling of cold, phosphorus-rich water to the shallow waters near shore stimulates all forms of sea life, from algae to animals. Their shells and bones, plus crystals of phosphorus, concentrate phosphorus on the ocean floor. Moving water—tides and currents underwater, streams and floods above sea level—sorts the heavy phosphate pebbles from the lighter sands, further concentrating the valuable nutrient.

The Mississippi River Delta region in southern Louisiana is losing land to sea level rise, subsidence, and hurricane damage. The mouth of the Atchafalaya River, a distributary of the Mississippi River, is an exception. It has been building two deltas for the past several decades. The Atchafalaya Delta exemplifies the importance of freshwater and sediment to maintaining and even building land in the delta region.

The Atchafalaya River branches away from the Mississippi River where the Red River joins it. The Atchafalaya takes about 30% of the combined flow of both rivers and carries the water and sediment south.

Just east of the Atchafalaya basin, land is rapidly disappearing from the Louisiana coast. Besides subsidence, sea level rise, and hurricanes, a lack of sediment input from the Mississippi River is also causing land loss, making the region more vulnerable to storms.

Besides the risk to wildlife habitats, coastal Louisiana supports more than 30% of the commercial fisheries in the United States, and five of the country’s top 20 ports are located there. Furthermore, in 2017, the USGS reported that a fifth of the country’s oil and gas is transported through the southern Louisiana wetlands.

The time series of Landsat imagery shows that the deltas do not progressively extend into the Gulf. They are affected by local conditions like tides and the timing of hurricanes and floods. So while the overall trend is extension and delta building, the deltas seem to temporarily contract at times. In the Landsat images, water is dark blue, and vegetation is green.

One of the world’s largest reserves of oil sits under the boreal forest of northwestern Alberta, Canada. The deposit covers about 142,200 square kilometers (54,900 square miles), an area a little larger than the U.S. state of Wisconsin.

Known as the oil sands region, it accounts for the largest segment of Alberta’s economy. According to Alberta Energy, proven reserves in the oil sands in 2016 were 165.4 billion barrels.

This series of satellite imagery focuses on the largest of the three oil sands areas in Alberta, the Athabasca region. Located just north of Fort McMurray along the Athabasca River, the mining of the Athabasca region has grown dramatically over the last three decades, and Landsat's 30-meter resolution is ideal for showing those changes.

The Ayeyarwady Delta—also called the Irrawaddy Delta—is a vast alluvial floodplain. The delta spans over 35,000 km² (13,500 mi²) and was once home to an extensive tract of mangrove forests, but deforestation has changed the landscape. One scientific study estimated that the delta lost 1,685 km² (651 mi²) from 1978 to 2011. This 50-year sequence of Landsat images shows the relatively rapid loss of mangrove forest.

The most noticeable land change in these Landsat images is simply the addition of land itself. In Bahrain, a nation of 36 islands in the Middle East, the sea is shallow enough along the northern and eastern coast to make the addition of land relatively inexpensive.

The main Bahrain Island is about 990 square kilometers; however, it took less than two decades for the coastal zone of Bahrain to increase by about 40 square kilometers. All of this added land is dredged from the seabed in massive land reclamation projects.

Besides the large land additions, an obvious increase in urban areas dominates the images. Bahrain’s 1970 population was 213,000; in 2023 it was estimated to be over 1.5 million. The country’s urban extent doubled between 1987 and 2013.

Even though oil is underground, Landsat images can reveal related land changes on the surface. The Bakken oil boom has made North Dakota the second leading oil producing state—behind only Texas. Evidence of this boom is apparent on the landscape.

The focus of this oil boom, which began around 2008, is on the Bakken formation of western North Dakota, northeastern Montana, and part of Canada. The Bakken formation constitutes one of the largest deposits of oil and natural gas in the United States. The Bakken is part of the larger Williston Basin, which, according to a 2013 USGS study, has 7.4 billion barrels of oil that is recoverable using today’s technology.

These Landsat images show the increasing number of oil platforms over just a few years, along with associated infrastructure changes. The overview images in this introductory section show the entire region that will be discussed in more detail in the following subsections.

The North Dakota oil industry took off in the 1950s. When oil prices dropped in the 1980s, that boom ended. Oil prices recovered by 1990, but the current boom didn’t hit until the technology of hydraulic fracturing, or fracking, came along in the 2000s. By 2008, drilling in North Dakota surged like never before and oil production increased dramatically.

The oil and natural gas within the Bakken are locked in a rock formation. Fracking uses a mix of water, salt, chemicals, and sand to fracture the rock. The fractured rock allows the oil to flow to the well.

The price of oil crashed again in 2014, halting most of the drilling. But this was only after North Dakota’s oil industry reached the milestone of producing 1 million barrels per day. In mid-2017, oil prices recovered to around $50 a barrel, stabilizing the situation in North Dakota.

Sometimes described as resembling a stingray or a tadpole, the Batagaika Crater is a widening chasm in Siberia and the world’s largest permafrost crater.

Multiple satellites have recorded the crater’s growth, from declassified satellite imagery collected in the 1960s to current multispectral sensor images from Landsat and Europe’s Copernicus Sentinel-2 satellite, to build a continuous view over the last 60 years.

Each exposed layer of the crater wall is like a snapshot in time, helping scientists understand the past climate. Layers of permafrost exposed at the bottom might be up to 650,000 years old. Scientists have also discovered mummified wildlife in the crater. In 2018, the remains of a 42,000-year-old foal of an extinct horse species were found.

Why this matters
As frozen permafrost soils thaw, they release carbon dioxide, methane, and nitrous oxide—greenhouse gases that fuel global warming.

Comparing the 1984 (high water level) and 2005 (low water level) images, there is a pale outline along many parts of the lake. When the water level drops, canyon walls that were once inundated are exposed again.

Referred to as the “bathtub ring,” this pale outline shows when the lake is below capacity. Calcium carbonate and other mineral compounds, many of them various salts in the water, attach themselves to the sandstone and leave behind this white mark. The top of the white mark is the high water mark. The only time the bathtub ring is not visible is when the lake is completely full.

Before 1950, the entire basin was covered by Bear Glacier and ended at a terminal moraine. By 1961, a small lake had formed, referred to as Bear Glacier Lagoon. By 1984, the size of the lagoon had doubled. It has continued to grow quickly as the glacier has retreated over time. People can now go kayaking among the icebergs on Bear Glacier Lagoon.

In August 2014, water from Bear Glacier Lagoon breached the moraine that separates the lagoon from Resurrection Bay. Lake levels dropped by 1–2 feet (0.3–0.6 meters). These glacier lake outburst floods occur regularly. The breach is visible in the extreme close-up in the 2014 Landsat image, in which different infrared wavelengths were used to make the breach more visible.

Satellite images of Earth help us observe locations that can be difficult to reach in person. Glaciers are sensitive to changes in regional and global climate, so scientists want to monitor them regularly. While some scientists study glaciers in the field, the Landsat satellites allow many others to monitor glacial change from the comfort of their office.

Bear Glacier is an outlet glacier of the Harding Icefield in Kenai Fjords National Park, Alaska. Glaciers form when fallen snow compresses into an ice mass over many years; the process usually takes centuries. The ice then flows to lower elevations. Besides showing visible retreat over the past few decades, Bear Glacier has also thinned about 2.5 feet (0.75 meters) per year from the early 1950s to the 1990s. 

Since Bear Glacier and many other remote glaciers are largely inaccessible, satellite images provide important insights into how they change over time.

(Black stripes run through some of the images because of the Scan Line Corrector failure on Landsat 7 in May 2003.)

These images show the growth of Beijing from 1977 to 2022. In the images, the blue tones representing buildings and pavement spread outward, replacing the red tones of natural and agricultural vegetation. The city has now grown far beyond its traditional core around the Inner City, which is visible as a bright rectangle in the zoom-in images.

Beijing has grown and changed remarkably in the "reform era" since 1979, in its own distinct pattern. U.S. cities, for example, are often shaped like a circus tent, with a sharp peak of skyscrapers in the center, sloping off to mid-rise buildings and then low suburbs of single-family houses. Beijing, in contrast, is bowl-shaped, with low historic buildings in its center, surrounded by many commercial skyscrapers and residential towers. Height restrictions have limited many buildings to 3 stories within 250 m of the Forbidden City, 10 stories within the Second Ring Road, and unlimited stories beyond. And single-family buildings are rare in Beijing, except in recent western-style suburbs built for foreigners.

Several distinct dynamics have shaped Beijing's growth. The state built a great deal of housing in Beijing during the 1950s, but little was built in the 1960s and 1970s, partly to discourage migration to the city. In the 1970s, many people who spent the Cultural Revolution in the countryside returned to Beijing, and others came seeking jobs. Married couples increasingly sought their own home after marriage rather than living with their parents. By the late 1970s, housing was scarce and crowded. In 1979, along with new reforms, came a boom in housing construction that was much-needed. Beijing's 2021 population is estimated at just over 19.4 million, with a population density of just over 4,600 people per square km.

In the more socialist era of 1949–1979, most Beijingers lived and worked in the same place. These "work units" included communal dining halls and infirmaries. So the city was not highly differentiated into office, shopping, industrial, and residential areas. There were few reasons to travel across town often. This has also changed in the reform era; housing is typically still tied to a job, especially for the many state employees, but this housing is not at the workplace. Many work-units buy floors of apartment buildings, or other blocks of housing, so many coworkers live together.

In the 1980s, many industrial plants were moved from the central city to outlying areas. Much of the new housing was also outside the Third Ring Road, in medium- and high-rise buildings often built on former agricultural land. In the central city, office districts and shopping districts have been built or expanded. Many new buildings serve the increasing number of foreigners doing business in Beijing.

Partly because people's daily activities now occur in separate parts of the city, traffic has increased greatly, and congestion is a major problem. An extensive subway line now operates in Beijing. By 2010, the Beijing subway network had 14 lines, 198 stations, and 336 km of track.

The Chinese government has provided a bicycle renting system in Beijing to try to relieve traffic congestion. But car use has risen dramatically in the last decade, and city planners are planning around the automobile and building expressways.

During the aquaculture expansion of the 1980s, cropland in the fertile valley was converted to catfish ponds. After the decline, many ponds returned to cropland. Some were left unused.

The Landsat images from 1972 and 1986 show that impressive expansion. Based on the 1972 image, which is coarser resolution than the later Landsat imagery, the land was either cropland or flat wetland before the catfish ponds were constructed.

Near Belzoni, Mississippi, many ponds have partially converted to cropland. According to the USDA Cropland Data Layer, the region shown in these images has converted to cotton, corn, soybeans, and rice growing. There are also woody wetlands in the former ponds.

The 2021 images span the seasons to show which areas have converted back to cropland. Actively growing crops appear bright green in the summer images. Those fields turn a washed-out pink after harvest. The areas that remain dark green in the fall are forested. By winter, those areas, too, become a faded brown and are the first areas to green up again in spring.

Where the water disappears throughout the 2021 images may be rice fields. Places where the water persists all year are catfish ponds.

Tourism is now a major part of the local economy. Ten thousand visitors climb the mountain every year, employing local people as porters and guides. The snow and ice are part of what attracts the tourists, some of whom come as a “last chance” opportunity, believing that the glaciers will soon disappear. Scientific estimates of that date vary, and some believe the glaciers on the side slopes may survive. If the glaciers do disappear, seasonal snow will still whiten the peak, but perhaps not in the dry seasons when most tourists come. In the end, on this mountain both science and economics are always drawn back, as if by some powerful cultural gravity, to the famous white landscape on its peak.

Besides hydropower, the dam has made river navigation easier. The river is now deeper and slower, allowing larger ships to travel on the river from Shanghai, at the river’s estuary, all the way to Chongqing, over 373 miles (600 kilometers) upstream from the dam. The Landsat images show straight lines next to the dam—the lock system that raises and lowers ships past the dam.

Historically, the Yangtze River has flooded catastrophically. The floods have caused thousands of deaths and damaged agricultural land. Flood control is one of the major anticipated benefits of the dam. The overall long-term extent of this benefit can be determined in the future as a wider range of high water levels are experienced on the river. In addition to flood regulation, water from the reservoir has been used to irrigate dry farmland during drought.

However, the project came with some downsides, including the relocation of over 1 million people. Other dangers added to the project’s criticisms. For example, much less sediment now reaches the lower portions of the river, which affects the intertidal wetland habitat at the river’s delta.

The reservoir’s water level is allowed to go down in summer to accommodate floodwaters. The water level rises again at the end of summer. These periodic water pressure changes destabilize the surrounding slopes, increasing the likelihood of landslides. Furthermore, the added weight of the reservoir’s water may be intensifying local fault activity; since the reservoir filled in 2003, seismic activity has increased.

The reservoir could also affect precipitation in the region. The lake effect in this mountainous region can be enhanced; moist air is forced upward as it reaches the shoreline, adding to low stratus clouds and fog. Additionally, the enhanced evaporation because of the lake can create a microclimate with different precipitation patterns.

The oil type mined in the Athabasca oil sands region of northwestern Alberta, Canada, is bitumen. This naturally occurring oil is so viscous that even at room temperature it acts like cold molasses.

The oil sand is quartz sand; each grain of sand is surrounded by a thin film of water, and then covered in the heavy oil. The bitumen is too thick to flow or to be pumped without first being heated.

Of the three oil sands areas in Alberta, only the Athabasca region has reserves shallow enough for surface mining. The Athabasca River, over tens of millions of years, eroded away the sediment that covered the bitumen, making it reachable. Surface mining causes a larger and more visible disturbance of the land surface than other types of mining. The surface mineable area there covers about 4,800 square kilometers (1,850 square miles).

We can’t see bugs from space, but we can see the effects of insect infestation in Landsat imagery. An unprecedented mountain pine beetle epidemic started in the Black Hills of South Dakota in 1996 and has damaged about 430,000 acres of forest land. The pine beetle, about the size of a grain of rice, is killing ponderosa and other pines throughout the Black Hills.

Normally, the mountain pine beetle contributes to the health of a forest by infesting and killing older and stressed trees, which helps make the forest more productive. However, the recent large outbreak is doing more harm than good. It can affect water quality. It can convert the forest from a carbon sink to a carbon source. And where insect outbreaks and forest disturbance caused by wildfire overlap, the effects can actually be both harmful and beneficial. All of the effects of an outbreak need to be monitored.

Mountain pine beetles usually live in small numbers. It’s normal for the population to boom occasionally, but the current epidemic is unprecedented. Beyond the Black Hills, pine beetle outbreaks have occurred extensively in many pine forests throughout western North America, from British Columba in Canada to New Mexico.

In these Landsat images, beetle infestation is typically indicated by a washed-out pinkish color as seen in the top center and lower right of the images. The more pronounced pink region in the lower left of these images is a burn scar from the Jasper Fire, which occurred in 2000.

In a desolate corner of Nevada, a playa surrounded by rugged mountains and described as dry, dusty, desolate, and devoid of vegetation comes to life the week before Labor Day every year for a unique arts festival.

Black Rock Playa in northwestern Nevada is part of the lakebed of ancient Lake Lahontan, a deep lake that existed as recently as 15,000 years ago. Lake Lahontan left fine sediments on the lake bottom to form the extremely flat surface. According to a detailed topographic study, the elevation of the playa varies by just 1 meter over 310 square kilometers.

The playa stretches 56 kilometers from the small town of Gerlach toward the northeast and the edge of the Black Rock Range.

Rainfall is rare during summer when daily high temperatures regularly exceed 37°C, making the surface hard-packed and dusty. Snowmelt flows into the playa in the spring to smooth out the surface. The clay minerals on the lakebed expand when wet and then contract as they dry to form a cracked pattern.

Black Rock Playa is managed by the Bureau of Land Management (BLM) as The Black Rock Desert–High Rock Canyon Emigrant Trails National Conservation Area.

The Black Thunder Mine, shown in the series of Landsat images on the left, has sent 2.2 billion tons of coal to U.S. power plants since 1977. It produces 4 tons of coal per second.

The images show the expansion of the open-pit mining operations at Black Thunder. The black lines are the coal seams, the layers of coal that formed over time and lie under the land surface. Lighter straight lines are stepped benches that allow trucks to drive in and out of the mine.

The other major natural harbour on the south end of these images is Botany Bay. The runways of Sydney Airport stretch into the bay. The main north-south runway is 3,962 meters long and was built in 1963. The other runway that extends into the bay appears in the 2002 image; it was completed in 1994.

Another expansion seen in Botany Bay is Port Botany, a major shipping port for Australia. The port is in an ideal location because of the deep water channels of the bay and proximity to the open waters of the Tasman Sea. The most recent addition is seen in the 2013 image, which shows the development of 63 hectares of land.

The Breiðamerkurjökull glacier tongue, one of the largest in Iceland, flows from Vatnajökull, Iceland’s largest glacier. According to descriptions in historical accounts, this glacier tongue advanced toward the Atlantic Ocean up until the turn of the 19th century. Since about 1930, it has been in full retreat.

In these false color Landsat images, vegetated land surfaces appear red. Snow and ice are white. The Vatnajökull glacier is the bright white area in the upper left. Outlet glaciers streak away from it toward the Atlantic Ocean in the lower right. Breiðamerkurjökull is the largest glacial tongue on Vatnajökull and is featured in the center of these images.

(Black stripes run through the 2006 image because of the Scan Line Corrector failure on Landsat 7 in May 2003.)

Cities that are growing this rapidly must also show accompanying infrastructure changes. The additions of bridges, highways, railroads, and airports are intended to merge the cities of the delta into a single megalopolis.

One ambitious project is the Hong Kong-Zhuhai-Macau Bridge, which opened in 2018, to connect the three cities and cut the travel time from Hong Kong to Zhuhai from 3 hours to 30 minutes. Visible as a long, thin line across the bay, the bridge-tunnel system includes 42 kilometers of bridges over water and a 7-kilometer tunnel. The tunnel allows ships to enter and exit the bay and runs between two artificial islands. The entire system is about 15 times longer than the Golden Gate Bridge. The total cost of bridge was $7.56 billion.

Built to withstand an 8.0 earthquake, the bridge makes it easier for goods from the entire PRD to be transported to Hong Kong’s international airport for export. Speaking of the airport, a third runway was added north of the existing runways, 3,800 m long and built on 650 hectares of reclaimed land.

The natural color image from Europe's Copernicus Sentinel-2 satellite shows the bridge at 10-meter resolution. Ships are visible in the water, including the wakes behind the ships.

Building Sea City is a massive and challenging engineering project that requires constant innovation. As seen in the 1994 image from Landsat, the area is a natural estuary with tidal creeks. The design of Sea City follows these existing tidal creeks to bring water inland from the Gulf.

The first phase of construction began in 2003. The 2004 Landsat image shows the first artificial waterway. Eventually, the sea will be brought inland to the desert by about 9 kilometers on what was once desolate unusable salt marsh. The lagoons created are 3–4 meters deep on average.

The water in the lagoons needs to be flushed and kept circulating so it doesn’t become stagnant. With the Gulf’s tidal range of 2.7 meters, this flushing happens in the waterways of Sea City naturally. Farther inland, however, tidal action needs a little help. Giant gates help control the flow of the tides and ensure circulation of the entire lagoon system. It works like a natural pump. Testing of the seawater has shown that its quality is excellent.

One of the most studied ice shelves in Antarctica has recently seen big changes. While the calving process is a normal part of an ice shelf’s lifecycle, recent rifting and iceberg calving may mean that the Brunt Ice Shelf is in a period of instability. It could also be an indicator of the future of other ice shelves in this region.

Landsat satellites have watched the ice shelf for nearly five decades. In 1971, a calving event reduced its extent. This occurred just before the first Landsat launched in 1972, so the earliest Landsat observations of Brunt came during the Antarctic summer of 1972–1973.

And now, Landsat 9 has joined Landsat 8 in observing the changing rifts on the ice shelf.

The smaller city of Buraydah, northwest of Riyadh, shows the same pattern of urban growth and agricultural development. From 1972 to 1986, the population of Buraydah almost tripled, from 60,000 to about 180,000 people. The rapid growth continued, and the population was 378,422 in 2004 and 669,000 in 2020. The 48-year increase is over 1,000%.

New roads are visible in these images, and irrigated land has increased. Buraydah and Riyadh both lie in Saudi Arabia’s central corridor of settlement and development.

After a wildland fire, scientists at the USGS EROS Center quickly begin working on preliminary soil burn severity assessments. They provide results of this work to Department of Interior (DOI) Burned Area Emergency Response (BAER) teams and other local federal land managers. BAER teams consist of an interdisciplinary group of scientists that evaluate the effects of wildland fires and develop mitigation plans to protect valuable natural resources, protect human life and property, and promote landscape recovery.

“The soil burn severity map is a critical component for many of the BAER team postfire hazard mitigation prescriptions,” says Randy McKinley, a geographer with the USGS EROS Center, who routinely maps fires on DOI-managed lands for the Bureau of Land Management, National Park Service, Bureau of Indian Affairs, and the U.S. Fish and Wildlife Service.

The burn severity map, also called a Burned Area Reflectance Classification (BARC) map, is created using digital image processing techniques developed by USGS, USFS, and other scientists. The BARC is a preliminary soil burn severity map that is field validated and refined by the BAER team. The final map provides a synoptic view of large fires that is not easily obtained in a timely manner on the ground.

The BARC map is made by comparing NIR and SWIR spectral band values. NIR light is largely reflected by healthy green vegetation. SWIR light is largely reflected by ash and bare soil. The burn map exploits the relationship between these two bands. The best way to do this is to measure the relationship between these bands prefire and then again postfire. The areas where the relationship between the two bands has changed the most are most likely to be severely burned. The areas where that relationship has changed little are likely to be unburned or very lightly burned.

For example, Landsat 8 helped map destruction caused by the Cougar Creek fire near Mount Adams, 75 miles northeast of Portland, Oregon, which started on August 10, 2015. In the three images to the left, snow appears cyan on its peak. The postfire Landsat image from September 11, 2015, shows where the previous green vegetation south and east of the mountain is now charred and appears in shades of red. In the burn severity map, dark green is non-burned, light blue is low burn severity, yellow is moderate severity, and red is high.

The timely delivery of BARC maps, generally in less than 2 days after image acquisition, would not be possible without the USGS capability to efficiently downlink, process, and distribute Landsat and other satellite data. USGS hydrologists and soil scientists routinely request BARC products to obtain a better understanding of postfire erosion and water quality issues. McKinley adds, “BARC maps have also proven to be a crucial data layer for the modeling and prediction of potentially destructive postfire debris flows.”

EROS responds to dozens of requests for burn mapping support each year. It’s not possible to get such a quick and complete assessment without satellite imagery. Landsat’s 30-m resolution is optimal for providing the detail suitable for landscape scale wildland fire mapping. When Landsat data are not available, imagery from the NASA EO-1 satellite, ESA’s Sentinel-2, and satellite sensors such as Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Moderate Resolution Imaging Spectroradiometer (MODIS) provide options for developing a complete picture of landscape change caused by wildland fire.

A unique event takes place every year on Black Rock Playa, Nevada. Burning Man is a weeklong arts and culture festival that ends on the Saturday of Labor Day weekend with the burning of a huge wooden effigy.

Part of the event is the construction of a temporary metropolis named Black Rock City. Building of the temporary town starts about 6 weeks before the event. This is the most visible product of the event in satellite images.

Besides the city’s radial roadways, the images show a pentagon surrounding the city. This “trash fence” catches wind-blown garbage to keep it from spreading throughout the playa. A major policy of Burning Man is to leave no trace. All debris must be cleaned up after the event is over. Participants must pick up all MOOP, which stands for Matter Out Of Place. The Bureau of Land Management (BLM), which grants the license for the event, monitors the cleanup.

A Landsat 8 image from October 16, 2018, shows not only the temporary nature of the metropolis but also that cleanup is evidently still in progress on that date.

Burning Man began in 1986 in California with 20 attendees and a 2.4-meter effigy. The festival’s first year at Black Rock Playa was in 1990, when the event had outgrown its California beach location. The temporary city that year had a population of 350 and the effigy was 12 meters tall. The 2018 event included 70,000 people. In recent years, the height of the entire effigy has exceeded 30 meters.

Usually located in the southern portion of the playa, the festival location changes slightly every year. Can you find the festival location in the 1996 image? (Look in the upper right of that image.) How about in 1999? (Extreme southwestern part of the playa.)

The city becomes easier to spot as the event grows larger. In the 2018 image, Black Rock City spans nearly 5 kilometers across. But its area covers only about 3 percent of the entire playa.

Burning Man went virtual in 2020 due to COVID-19. Its temporary city was absent from satellite imagery on Labor Day weekend for the first time in decades. After another year without a festival on the playa in 2021, Burning Man returned in 2022.

Check out this hi-resolution aerial image from the National Agriculture Imagery Program (NAIP) of Burning Man 2019.

As expected in the Atacama Desert, Landsat doesn’t detect much vegetation—only some green along the Río Loa and next to the city of Calama. Calama has seen a rising population because of the influx of mine workers. The images show this visible urban area expansion. Notice the airport expansion that took place between the 2010 and 2016 images.

Look at the zoomed in images by the coast. Can you tell the peaks (that is, the ridges) from the valleys? It may seem easy, but you may be tricked by a common optical illusion in satellite images called relief inversion.

All Landsat images are designed to be morning views, so all of these images were taken in the morning. The Sun is to the east and south, so these images are lit from below and to the right. This causes the western and northwestern slopes to appear dark because they face the sun less squarely, and so are less illuminated.

However, we unconsciously expect to see images lit from above. This tricks the brain into believing that mountains are valleys or that craters are mountains. If you look at the image upside-down, with the sun angle generally from the top of the image, you will probably see the image differently.

On the east end of the largest portion of the Danjiangkou Reservoir, a bright line extends to the east and north. This canal takes water from the reservoir 1,400 kilometers to Beijing. This water will benefit over 100 million people.

Construction of this central route of the South-North Water Transfer Project began in December 2003. Beijing began receiving water from the reservoir via the canal in 2014. The entire project is the biggest interbasin transfer scheme in the world.

Historically, water flowed slowly southward through the Everglades in a wide swath. Record floods in 1947 and 1948 led to the construction of a massive flood control project. It served to prevent flooding and store water during dry periods. It also allowed for further development of the growing urban area on the Atlantic coastal ridge.

The project established three Water Conservation Areas (WCAs), one of which is the Loxahatchee National Wildlife Refuge. These areas are delineated in the Landsat images, clearly divided by the levees and canals. Also visible are the Big Cypress National Preserve, Everglades National Park, and Everglades Agricultural Area.

Another part of the project is the 100-mile-long eastern perimeter levee, a 3- to 6-meter high earthen berm built to prevent flooding of farmland and urban areas. It runs along the eastern edge of the WCAs, marking a clear separation between the WCAs and urban areas such as Miami, Fort Lauderdale, and Coral Springs.

Along with facilitating the further growth of the urban areas of greater Miami, the other upshot of the project was that the natural flow of water was interrupted, changing the hydrology of the region. The gradual sheet flow of freshwater is diminished, and instead sudden pulses of water are delivered by the canals. These sudden releases caused decreases in the numbers of fish species.

Along some coastlines, long, narrow islands stand guard. These barrier islands are attractive to tourists, but they also protect the mainland coast from storm surge and are important beach, dune, and marsh habitats. Those islands do take a beating though.

These images focus on the southeastern elbow of Cape Cod, Massachusetts. Wave action, currents, winds, and tides are constantly changing the barrier islands here. Strong storms can change them quite suddenly.

In 1984, a nearly unbroken barrier island lines the Massachusetts coast at Chatham. To the south, Monomoy Island extends into the ocean like a teardrop. The other subsections of this Earthshots page show over 35 years of changes to these barrier islands as seen by three different Landsat satellites.

Farming doesn’t always mean tilling the ground for crops. In the flat valley along the Mississippi River, in a distinctive region of northwestern Mississippi referred to as “the Delta,” rich soils do support agriculture. But the flat land and abundant groundwater are also suited to aquaculture. Aquaculture simply means cultivating aquatic plants or fish for food. In this part of Mississippi, it means catfish farming.

Catfish are raised in Arkansas and Alabama, but Mississippi has led the nation in catfish production since the 1980s. The farm-raised catfish eat high-protein food pellets made of soybeans, corn, wheat, vitamins, and minerals. The pellets float on top of the water, so the fish don’t eat like wild bottom-feeding catfish do. The result is healthier fish with a cleaner, milder taste.

The Mississippi River meanders down the left side of these Landsat images. Green indicates vegetation: Bright green shapes are cropland, and darker green shades are forests. Surface water is dark blue. Besides the Mississippi, other streams and oxbow lakes are scattered across the region. The catfish ponds are the distinctive blue squares and rectangles among the cropland. The washed-out pink areas are harvested fields.

The catfish industry grew rapidly in the 1980s and 1990s. The blue-tinted shapes in the Landsat images mark the ponds where the whiskered fish are raised. The ponds are built above ground with levees, and the water in the ponds is 4–6 feet deep.

Catfish pond acreage reduced by more than half from 2003 to 2013. Rising costs and low-priced imports from China and Vietnam led to the decline.

At the same time, increased productivity from technological efficiencies led to higher yields and less land needed for the ponds. Among those efficiencies was the development of a hybrid catfish species, a mix of Ictalurus punctatus (channel catfish) and Ictalurus furcatus (blue catfish).

The hybrid grows faster, is easier to harvest, and has greater tolerance to crowding, so less area is needed to grow more fish. The business term for that is “increased operational intensity.”

Other technological efficiencies reduced costs and spurred growth in the 2010s, including electric paddlewheel aerators, automated oxygen monitors, and pumps to circulate the water. Ponds are now divided into separate sections for treating wastewater and for the fish. These split ponds make treating the water more efficient.

Some of the dark lines in the images might look like roads. Those lines are a transportation network of sorts, just not transportation for people. They are cattle corridors that connect grazing lands (dark patches) and sometimes connect to villages. They are lined with hedges to keep the cattle out of the crops.

One line that goes all the way across these images is indeed a road. It passes through the city of Bankass. But the other lines are cattle corridors.

The diversion of water from the rivers for agricultural use is probably the most significant cause of Lake Urmia’s decline. Several dams have also been built on rivers that flow into the lake. Since 1996, droughts have further contributed to the lower lake levels.

Rainfall in 2018-19 brought water levels back up. That rainfall did not bring a permanent restoration of the lake, as the 2023 image shows.

No single fix can help the lake recover. But the continual monitoring from Landsat helps decision makers plan for the best solutions.

High-resolution imagery from the WorldView satellite and aerial photos show details that moderate resolution satellite imagery cannot. The result of the land loss and its effect on Isle de Jean Charles becomes clear in these images.

The loss of land in southern Louisiana has several causes.

• Dams Upriver, dams trap sediment that normally flowed to the delta and built it up.
• Subsidence The land in the Louisiana delta has always sunk naturally. Faults contribute to regional subsidence, and sediments naturally compress over time. Deposits flowing from the Mississippi River continually replenished and built up the land. Much of this sediment is now trapped by upstream dams, taking away the rebuilding process.
• Sea level rise The long-term gradual rise in sea level combined with that subsidence increases the land loss more than either factor alone.
• Canals 10,000 miles of canals dug through the marshland, built for oil and gas production activities, bring saltwater farther inland, which degrades freshwater marshlands.
• Hurricanes Storm surge and waves can propagate farther inland because of land loss, making matters worse. Hurricanes erode the soft land from the coast and can damage both vulnerable and healthy marshlands.

The saltwater that washes farther inland also invades the soil and has made the area no longer good for farming. As the marshland retreats, the saltwater enters bald cypress swamp and kills the trees.

Island Road
The only road into or out of the island is the 2-mile-long Island Road. When it was built in 1953, land and marsh surrounded it. Tribal members hunted and trapped on the land around the road. It now cuts across open water. It often submerges during high tide, and erosion continues to eat away at the roadbed.

If you could speed up time and watch a fast-growing city like Las Vegas change, what would it look like? From the perspective of the Landsat satellites, it’s a stunning lesson in urban growth. Watch Las Vegas’ rapid expansion in these Landsat images dating back to 1972.

In each image, bright red indicates actively growing vegetation. This makes golf courses easy to spot, and their development can be tracked along with the residential areas that surround them.

The desert landscape gradually becomes covered with streets, highways, and development as time goes on. A plot of very light tan can sometimes be seen right before a new residential area is built. This indicates a clearing of the land.

Other natural bright areas also appear around the urban development. The bright reflection indicates the presence of salts, minerals, and clays in the sediment. Water once settled in these flat, lower elevation areas and these minerals remained. The brown-tan regions surrounding the city are likely steeper slopes where flowing water rinsed out those minerals. Darker tones indicate coarser material, and lighter tones are fine material such as clays that have a higher reflectance.

Each image represents one year from 1972 to 2024. Landsats 1–5 and Landsat 7–9 are represented, which demonstrates the value of the past Landsat data along with new data for monitoring change over time. Landsat images are available to the public at no cost at the USGS Global Visualization Viewer (http://glovis.usgs.gov) or EarthExplorer (http://earthexplorer.usgs.gov).

Watch this animation of Landsat images of Las Vegas, or view the individual images at your own speed below.

The new shoreline extends east of the city all the way to the airport on the island’s tip. In the mid-1970s, the government moved the main international terminal from Paya Lebar to Changi, partly to allow more distance between the planes and new, higher skyscrapers downtown.

In the 1989 image, on the east end of the island, you can see the old and new runways, parallel and a few miles apart. Planes now land where once was only water. A further extension of the land on the eastern tip was built for Chengi Air Base, visible in the 2000 image and later.

A feature known as Chasm 1 is prominent in the Landsat imagery. This crack reactivated in December 2012 after no movement for 35 years. The Landsat images show rapid growth of the chasm, especially in 2018 and 2019, as it extended toward the McDonald Ice Rumples.

In early 2019, Chasm 1 was extending north as fast as 4 kilometers per year, and from 2012 to 2021, the rift widened almost three-fold.

On January 22, 2023, an iceberg the size of Houston finally broke off the shelf. Landsat images show the area a day before the break and a few days after. The new iceberg, named A-81, will be carefully tracked by satellites as it floats into the Weddell Sea.

The time series of images also shows Chasm 1 moving westward with the flow of the ice shelf.

The close-up Landsat images that accompany this section show an obvious checkerboard pattern in the forest. These lands are known as “O&C” lands, which stands for Oregon and California Railroad. Land granted to O&C in 1866 was every other square mile, which formed the checkerboard pattern seen in the imagery. These lands now belong to the federal government, managed by the Bureau of Land Management (BLM).

In these images, the squares that remain dark green generally are lands that belong to the BLM. In some of those squares, there is clearcutting and regrowth taking place in this time frame. Adjacent squares, however, have a more noticeable change in tan or white spots, indicating more frequent clearcuts in the logging/reforestation cycle.

View an animation of this area to see the changes as they happen.

A nuclear accident devastated the region near Chernobyl, Ukraine, on April 26, 1986. These images show the area around the nuclear power plant three days after the accident, and then years and decades after the accident.

The Landsat 5 image from April 29, 1986, was the first civilian satellite image of the accident. The data from Landsat were used to help confirm that an explosion had happened at Chernobyl and that the plant had been shut down.

Cheyenne Bottoms in central Kansas is the largest inland wetland in the United States. A 41,000-acre natural basin, the wetland is a key stopover for a multitude of migrating birds to eat and rest. The Cheyenne Bottoms Wildlife Area covers nearly half of the basin.

The wetland’s water level changes with precipitation and surface flows. For example, 2007 was a wet year, and 2013 was a dry year until heavy rain in late summer partially replenished the marshland.

The lines in the basin are roads on top of dikes, built in the 1950s to impound water in five pools and manage water levels. Further subdivision of the wetland pools took place in the 1990s. Water levels in individual pools are periodically flooded or drained to control invasive vegetation (such as hybrid cattails) and promote desirable aquatic vegetation. Additionally, small grains such as Japanese millet are sometimes seeded to provide supplemental food resources, then flooded to make the food available to foraging waterfowl.

The crops surrounding Cheyenne Bottoms include alfalfa, sorghum, wheat, corn, and soybeans, along with pasture.

Two intermittent streams, Blood and Deception creeks, flow into the Bottoms from the northwest. Canals were built to divert water from the Arkansas River and Wet Walnut Creek to provide a source of supplemental water to the wetland. However, drought kept the Bottoms dry in 2022.

The Atacama Desert of northern Chile has minimal vegetation. But it has ample mineral wealth: large amounts of copper, gold, silver, and other industrial metals. This includes the world’s largest open pit copper mine and the second deepest open pit—the Chuquicamata Mine.

In operation since 1910, the largest open pit at the mine measures 1 kilometer deep, 3 kilometers wide, and 5 kilometers long. New York City’s Central Park could fit inside it.

Evidence shows that copper has been extracted in the region for centuries. Indigenous people worked the copper deposits in pre-Hispanic times to make weapons and tools. The mine now produces 650,000 metric tons of copper annually.

Nouakchott was a small fishing village for hundreds of years. As recently as 1950, it had only about 200 residents. Drought throughout the 1970s brought migrants to the city, and its population swelled to about 150,000 in 1980. It now has just over 1 million people, and its urbanized area has changed from 5 km² in 1965 to 150 km² in 2016.

A 1965 close-up of Nouakchott from the Corona satellite shows the extent of the city at that time. Since then, the city’s expansion has been horizontal, spreading outward. Much of city’s urban growth occurs in informal settlements, which can be seen in the later Landsat images in the varying patterns of urban areas. Streets go in multiple directions and sprawl unevenly across the desert from the city’s center.

This may be against conventional wisdom, but this growing city in the desert is at high risk for flooding. The city is mostly below sea level and vulnerable to rising groundwater levels, seawater intrusions, porous soils, sand extractions, and heavy rains in low-lying areas.

In recent years, the number of rainy days has been increasing. The biggest problem is that a large amount of rain can fall in a short period of time. Since the groundwater level is high, and the type of soil there is not very good at absorbing even a small amount of rain water, rain cannot infiltrate into the ground. These factors lead to a city at high risk. In fact, heavy rains in August 2013 caused flooding in Nouakchott and south-central Mauritania.

A logging strategy that’s easy to spot in the Landsat imagery is clearcutting. All the trees in an area are harvested, and then replanting begins immediately. Replanting must be completed within 2 years of harvest. In Oregon, about 40 million new trees are planted each year. According to the Oregon Forest Resources Institute, the reforestation success rate is 95% on private land.

Clearcutting is a major change to the forest. Clearcuts look unattractive, and they disrupt wildlife habitat. The clearcut area can also increase streamflow in that area, and the soil can erode more quickly until reforestation occurs. Therefore, in Oregon, the size of clearcuts is limited to 120 acres. They are also limited further when near highways. Forested buffers must be maintained along streams, lakes, and wetlands. This protects against possible increased streamflow erosion and maintains wildlife habitat.

There are actually some positive effects to clearcuts. They create open space in the forest that many plants and animals need to flourish. The full sun promotes rapid regrowth of Douglas fir and other species that need full sun. Also, clearcuts are generally temporary. Oregon requires prompt reforestation.

Landsat 8’s near-infrared and shortwave infrared imaging shows the pockmarked desert, perhaps more reminiscent of other planetary bodies than Earth. The age of the craters just about spans the entire Cold War. The first underground test was November 29, 1951; the last September 23, 1992.

Despite the hundreds of tests conducted throughout the Cold War years, only about 7% of the Nevada Test Site has been disturbed.

While nuclear explosions no longer rock the site, now called the Nevada National Security Site, nuclear weapons research still takes place there based on those tests. Computer simulations can help predict what happens during explosions.

The craters have also been used as Mars analog craters. Since access to the site is restricted, the craters are relatively undisturbed. That, along with the dry climate, helps scientists better understand craters on Mars, especially the types of craters that effectively expose near-surface material that Mars rovers and drones can study.

On Earthshots we typically show “multispectral composites”—single-date images that combine three different wavelengths into one image. The example used in this section shows a different combination of infrared wavelengths than was used on the 2016 image from the “Interpret the Images” section. In this image, the clearcuts are pink against the bright green of the forest. This combination of infrared wavelengths makes the clearcuts that have occurred from one year to the next stand out more clearly.

We don’t often examine change over time in one image. That’s what the colorful image in this section shows. It’s a “multitemporal composite”—one image that shows three different dates combined. This image shows a combination of Landsat images from 1994, 2009, and 2016. Red shows clearcuts that were evident in the 1994 image. Green shows clearcuts that took place by 2009. And blue shows clearcuts that occurred by 2016. Darker tones are areas of forest that did not change in this time frame. This way of examining the imagery shows that logging has affected nearly the entire landscape shown, something that may not be evident when looking at a single-date image.

People derive many ecological and economic benefits from forests, and Landsat can help forest managers monitor changes to ensure these resources are available for future generations.

Some landscape changes around the world happen at glacial pace—very slowly—and have not been captured in the satellite era. However, glacial pace would not describe the changes to Alaska’s Columbia Glacier over the past few decades.

Columbia Glacier is a large tidewater glacier that flows south out of the Chugach Mountains in Alaska to Prince William Sound. Since 1980, its terminus has retreated 20 kilometers to make it one of the most rapidly changing glaciers in the world.

When it was surveyed by British explorers in 1794, Columbia’s terminus was at the northern edge of Heather Island. It stayed there until 1980, when its current rapid retreat began. A 300-meter deep fjord now replaces the portion of the valley once occupied by the glacier.

This series of Landsat images shows the rapid retreat, including an acceleration of the retreat in the early 1990s, followed by slowdowns in 1994–1997 and 2000–2006. It has picked up the pace of retreat again since 2006. Columbia has also become narrower, as shown by the expansion of bedrock areas in the images.

The false-color images use shortwave-infrared, near-infrared, and green wavelengths to highlight these changes, where snow and ice appear cyan, vegetation is green, open water is dark, and exposed bedrock is brown.

Why this matters

Land-based ice flowing into the ocean from tidewater glaciers is a leading cause of sea level rise. A 2015 study found that Columbia Glacier sent about 4 gigatons (billions of tons) of ice into the ocean every year from 1994 to 2013. An increasing rate of iceberg calving can also pose a danger to ships in shipping lanes.

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The satellite images presented on the Earthshots Web site are not intended to be used for scientific interpretation, only for educational purposes. Landsat data are freely available and may be downloaded from the USGS Global Visualization Viewer (GloVis) at http://glovis.usgs.gov or EarthExplorer at http://earthexplorer.usgs.gov.

The Landsat 5 image acquired before April 26 shows heated water being pumped from the plant into the adjacent cooling pond and circulating counterclockwise. Landsat 5’s thermal infrared band shows that heated water as orange, then gradually turning yellow then blue as it cools. But the image from April 29 indicates all the water in the pond is the same temperature, evidence the plant was not operating. As the first civilian satellite to image the disaster, Landsat 5 helped confirm the disaster had happened, and this was part of the evidence.

In just the past few years, the cooling pond by the former power plant began drying up. Satellite images clearly reveal a rapid decrease in water level.

Soon after the accident in 1986, radioactive material entered the pond from atmospheric fallout. The contamination went into the pond’s sediment and was shielded by the water. In 2014, the Ukraine stopped pumping water into the pond from the Pripyat River in order to save money. The consequence of this action could be to expose radioactive sediment to the air where it can be dispersed by the wind.

Often described as one of the world’s best cities to live, Copenhagen is growing steadily. That growth comes with challenges to keep it a desirable place to live.

In these false-color Landsat images, the urban areas of Copenhagen are shades of purple. Vegetation appears green, and farmland appears bright green when crops are growing and pink when the fields are fallow.

The Øresund Strait separates Copenhagen from Malmö, Sweden. The strait and other water bodies appear black.

In the time that these images span, the population of Copenhagen has grown from 478,615 in 1985 to 580,184 in 2015. But the population of greater Copenhagen in 2014 was 1,246,611, up from 1,084,885 in 2006.

To get an even more detailed view of this region, we can actually go back to satellite imagery from 1967. This pre-Landsat imagery, while black-and-white, helps to extend the record of land change on the Earth. These images are declassified reconnaissance satellite images and show detailed and informative views of the Seno Plain.

Comparing WorldView-2 with Corona shows the pattern of change that we see in Landsat, only in more detail. In the grayscale Corona imagery, bright areas are cultivated cropland. Dark gray is grass with shrubs and trees. In the natural color WorldView-2 images in 2011, much of that fallow or grassy land has converted to agriculture, indicated by light tan.

The resolution of the Corona image is 6 feet. For Landsat, it’s 30 meters. So in Corona, even single trees can be distinguished.

The more up close images show a few villages in higher detail and demonstrate that they have expanded with the growing population. The darker gray at the bottom of the 1967 image gives way to tan in 2011, which is intensive cropland. Those cattle corridors are also clearly visible in this WorldView-2 image.

Wildland fires can leave behind scorched mountainsides with no trees or other vegetation to stop rain-driven mudslides or dangerous debris flows. When such potential exists, the shortwave infrared (SWIR) and near-infrared (NIR) spectral bands of the Landsat satellite sensors help to identify those possibilities quickly.

The six images displayed show prefire conditions in 2014 and the progression of the Cougar Creek Fire in Washington on the eastern slopes of Mount Adams over the several days that it burned in 2015. Lightning started the fire on August 10, 2015, and it was not contained until mid-September. While it’s interesting to see the progression of the fire, it’s the prefire and postfire images that are really important for burn severity mapping.

(Black stripes run through the Landsat 7 images because of the Scan Line Corrector failure on Landsat 7 in May 2003.)

These close-up images from Landsat show the Seno Plain in a bit more detail. The images were acquired during the dry season, so crops were not growing at the time. However, the images do show evidence of how intensely the land was being used for agriculture, indicated by the lighter toned patterns. As in the wider views, the Bandiagara escarpment is the feature on the left of these images.

The 1972 image shows that farmers practiced crop rotation, leaving some land fallow. The fallow fields are represented by dark patches. In 1986, however, much of the fallow is gone, and there is even less of it by 2016. Bright areas dominate the 2016 image, indicating wall-to-wall cropland over the plain. The darkest patches are grassy fallow areas and are either protected lands or used for cattle grazing.

Dallas-Fort Worth International Airport, between Dallas and Fort Worth, opened the year of the first Landsat image shown here, 1974. A new runway added after 1974 can be seen west of the airport in the 1989 image. The north-south runway on the east side opened in 1996 and appears in images from 2000 and later. The airport covers almost 30 square miles, making it the second largest airport in the United States.

These images show the Dallas–Fort Worth metropolis in northeastern Texas. This city has grown significantly in recent decades, from 2,378,000 in 1970 to 7,943,685 by 2022.

Spongy moth caterpillars devour the leaves of hardwood trees, causing the greatest damage in late June as the larvae reach maturity. The caterpillars are hungry little buggers, and they’re not picky eaters. Even though they prefer oak and aspen, they feed on other deciduous trees such as maple, birch, poplar, willow, apple, and hawthorn, and can go after coniferous trees during a large outbreak.

During a dense population boom, they eat all the leaves on a tree and can even defoliate entire stands of trees. Beginning in 2016, the combination of visible and infrared imaging from Landsat revealed the extent of the damage the outbreak has caused.

Healthy forest is bright green, but as the time series progresses, much of the green turns to faded brown as the infestation spreads.

Though spongy moth outbreaks are a fairly regular occurrence in the more southern portion of their invaded range, this outbreak was the first time spongy moths caused significant defoliation in New England since the 1980s.

How did they get here?

An amateur entomologist Etienne Léopold Trouvelot brought spongy moth eggs from France to Massachusetts in 1869. He was conducting experiments with the eggs possibly to see if the spongy moth could be an alternative to the native silkworm. The insects somehow escaped from his home and have affected the forests of the Northeastern United States ever since.

Visible in these images is one canal associated with the $62 billion South-North Water Transfer Project. Water resources are a concern in China because freshwater is distributed throughout the country unevenly. The south has abundant freshwater, but it’s scarce in the north. This project is an attempt to alleviate the water shortage in the north.

The entire project has three different canal routes that link China’s four major rivers (the Yangtze River, Yellow River, Huai River, and Hai River). The central route brings water from the Danjiangkou Reservoir north to Beijing. The reservoir was formed by the Danjiangkou Dam, completed in the 1970s. The height of the dam was increased from 162 to 176.7 meters above mean sea level between September 2005 and September 2013.

The water surface level of the Dead Sea is the lowest natural land or water surface on Earth at more than 400 meters below sea level. That level continues to lower as water from Dead Sea tributaries is diverted for irrigation. In the southern part of the sea, the salt and potash industries use water from the sea in evaporation ponds. Water is not quickly replenished in this closed basin, so the level continues to drop.

The sea is made up of a northern basin and a southern basin. Both basins were once connected by a strait (see the 1973 image), but the strait is now dry.

(Black stripes run through some of the Landsat 7 images because its Scan Line Corrector failed in May 2003.)

Every year in Bolivia, a swath of forest two-thirds the size of Delaware is cleared of trees. Most of this deforestation has taken place in lowlands along and east of the Rio Grande River.

Compared to most Amazon soils, the alluvial soils in these lowlands are very fertile. The flat landscape is relatively easy to clear. And rain forests have an abundance of one obvious thing important to farming—rain. Besides that, the area is close to a large market and distribution center, the city of Santa Cruz, which lies just outside of these images, about 7 kilometers off to the southwest. One more benefit to the land owners: when farmland becomes too eroded or compacted for crops, farmers change to cattle production.

Until the 1970s, sugarcane was the major crop near Santa Cruz. By the 1980s, the price for soybeans increased. Today, sugarcane is still an important crop, but industrial soybean production has become the most common crop.

Different deforestation geometries reveal different types of agricultural management. Most noticeable might be the groups of long rectangles, which are large-scale agricultural operations. These areas require large capital investments, use heavy machinery to prepare the land, and involve intensive production of annual cash crops, mainly soybean, sugarcane, and rice. Dark strips within these fields are windbreaks, needed because the soils in the area are fine and prone to wind erosion.

Small-scale agriculture is indicated by smaller irregular plots. Small-scale farmers here produce mainly rice, maize, and perennial crops, such as bananas. The forest is cleared perpendicular to a road in long rectangles, forming a “piano key” pattern.

The radial-shaped patterns are planned settlements called nucleos. The individual farms radiate outward from a central hub, which is communal land. Most of these settlements are located in the large area of colonization visible in the northwest part of the main images, the San Julian area. There are a few others; see if you can find them in the later images.

All of Madagascar is being threatened by deforestation, but this threat is most apparent in the Spiny Thicket region. Spiny Thicket has a naturally slow rate of growth and regeneration, making it especially vulnerable to the effects of deforestation. The primary threats are from small-scale but widespread clearing of trees for firewood, agriculture, and livestock grazing. Human population growth increases the demand on natural resources. This is part of the reason for the increased rate of deforestation here. For example, more land is needed for agricultural production.

Landsat images show more clearly the extent of changes to the Spiny Thicket ecoregion in southwestern Madagascar. Over the past four decades, rapid deforestation has occurred on both sides of the Linta River. Most of these images are from around the end of the rainy season (October to April) when vegetation is near its peak annual growth.

The primary cause of this deforestation is conversion to cropland and pasture. But the reasons for this conversion are varied.

Countries that have extensive tracts of rain forest build roads into remote areas to improve transportation of goods. Legal and illegal logging follows the road expansion. Once an area is logged, it becomes a prime location for agricultural development, which further clears the surrounding forest. These cleared areas are also prone to wildfires, which can further degrade the forest.

Governments sometimes encourage the development of the rain forest with subsidies and tax breaks. Pressure from the global market for timber and soybeans drives the agricultural development.

People are drawn to delta and coastal regions, and about 7.7 million people live on the Ayeyarwady Delta. Deltas can be productive agricultural areas because the soil is rich and the flat terrain and water provide easy access to water-based transportation. The Ayeyarwady Delta produces 35% of Myanmar’s rice. Cutting wood for fuel also contributes to mangrove loss, but most of the deforestation in this delta has been for rice fields.

A more close-up look at the eastern portion of the delta shows this degradation in more detail. As the sequence of images progresses, the bright green of healthy mangrove changes into a mottled green of degraded mangrove.

This mangrove loss could have implications for protecting people on the delta. The delta’s low elevation and flat landscape make it vulnerable to flooding from storm surges, as with Cyclone Nargis in May 2008. The mangrove forests provide a buffer for storm surge.

The monarch migration is an endangered phenomenon. Logging in the overwintering sites in Mexico reduces the area available for the monarchs. The Monarch Butterfly Biosphere Reserve, established in 1986, is intended to protect the overwintering areas. But studies have shown that deforestation has occurred within the reserve. Some of that deforestation can be tracked from space with Landsat imagery.

According to Monarch Watch, during the 2012–2013 season, monarch colonies occupied the lowest number of hectares of forest in the previous 20 years. But the 2013–2014 season was even lower. Recent seasons have seen a slight increase in area of forest occupied, but monarch populations this low are extremely vulnerable. Just one winter storm could severely decrease their numbers.

Landsat sensors use infrared reflectance. One of the wavelengths of light they use is called near-infrared. Actively growing vegetation reflects this wavelength, so when this wavelength is assigned the visible color red, vegetation is displayed as red in these false color images. As you take a closer look at the zoomed in areas in the other sections, watch for gray patches in areas that were once red. This indicates a degraded forest.

Not all of the reduction in the monarch population can be attributed to oyamel forest loss in Mexico. In the United States, expansion of agriculture and herbicide use are reducing the milkweed that the caterpillars need. Extreme weather conditions have also been harming the monarchs. Satellite imagery continues to be useful in tracking the monarch population in these overwintering sites and can help recover this remarkable migration.

The Huang He Delta has historically built up over a broad area because of its wandering ways. The river’s course in its lower reaches has shifted 11 times since 1855. The latest shift was in 1976. Before that, the river turned northward into the sea; in 1976, it took a different direction, heading east and carrying its sediment to build a new delta there.

The river now carries its sediment farther outward, creating an ever-changing delta.

At the mouth of the Atchafalaya River, a distributary of the Mississippi River, the Wax Lake Outlet is a prominent north-south waterway. This artificial channel in southern Louisiana begins just upstream of Morgan City and carries water straight down to the Gulf. The U.S. Army Corps of Engineers dug the outlet in 1941 to prevent severe floods.

After the Wax Lake Outlet was created, water carried sediment to its mouth and began to build a delta, all of it underwater at first.

After flooding in 1973, caused by an unusually cold winter and above average spring rain, extra sediment rushed through the Wax Lake Outlet and, for the first time, its delta became visible. Reeds and willows began to grow and stabilize the new land. Their roots hold on to the sediment to keep the ground stable.

A little less than half of the Atchafalaya River flows through the Wax Lake Outlet. The rest also flows south to the Gulf a little to the east and is building a delta there.

The rest of the Louisiana coastline is retreating because Mississippi River water flows through narrow channels that don’t allow sediment to settle—the sediment-rich water speeds directly into the Gulf. The Atchafalaya carries sediment more slowly, which allows it to settle in the broad, shallow basin and maintain the marshes.

In the late 1960s, the Indonesian government began working toward improving and expanding its economy. It encouraged people to move to the remote and less developed eastern islands. One of the industries it expanded was logging. As workers cut down the primary forests, the forests were not allowed to grow back into secondary forest. Instead, they were planted as palm oil plantations. Palm oil trees are native to Africa and were found to thrive in Malaysia and Indonesia.

Palm oil demand is up as demand for biofuels rises. Biofuel producers say palm oil is a renewable alternative to fossil fuels. One hectare of a palm oil plantation can produce 10 times as much oil as other oilseed crops, including soybeans.

The palm oil plantations show up clearly in Landsat images in the middle of the undisturbed rain forest. Road networks—the pink jagged lines—cut through the green of the rain forest. One road leads from the cleared forest to the river town Asike.

The first cleared area that appears in these images covers about 14,500 hectares. By 2014, another new planted region appears just south of the first cleared area. The next section shows those cleared areas in more detail.

Denver has all the classic marks of substantial urban growth over the past few decades. Satellite images reveal expanding residential areas, industrial zones, and new freeways that loop around the metropolitan area. Also visible is one of the largest airport building projects in U.S. history.

False color imaging from Landsat that combines shortwave infrared and near-infrared bands shows growth of the city. Bright green is vegetation, so parks and golf courses are the brightest green; dark green is the forested areas in the Rocky Mountains; and the more mottled green shades are the residential areas of the city. Purple hues represent streets, highways, and other mostly unvegetated infrastructure.

Denver is experiencing post-1950 growth similar to other western cities like Los Angeles, Phoenix, and Dallas. The Denver metropolitan area expanded in urbanized land from 150 square miles in 1950 to 499 square miles in 2000, primarily onto prairie and agricultural lands.

The word desertification, if split into its roots, logically would mean the event of non-desert land becoming desert, but it is not quite so simple. Desertification is usually defined as a process that happens to land that is already normally arid (dry) or semiarid and it's not just caused by drought. In fact, the crucial factor is a decline in the biological productivity of the land—the amount of vegetation that grows (either naturally or that people have planted)—as well as the animal life supported by the plants. If desertification continues, eventually the land becomes a desert, with increased wind and water erosion, decreased soil fertility, and decreased water-retention capacity. Plant and animal communities decline in number and diversity, as many species can no longer survive.

Desertification is usually a patchy development, spreading outward from pockets of land where the vegetative cover has been harmed or destroyed, so that sandy dry soil begins to drift and vegetation is unable to reestablish itself.

In western Africa, boreholes (water wells) are often the points of this vegetation disturbance, because they attract livestock, which overgraze the land nearby. But in this example, the point of disturbance is a paved highway that was built to connect Nouakchott, the national capital of Mauritania, with the regional capital Rosso. Besides travel and transportation, the highway also encourages building and settlement. All of these activities consume vegetation for grazing, fuel, and building material. The vegetative cover becomes disturbed, some sandy soil begins to drift, and the process of desertification is underway.

In these images, the disturbances the highway causes become evident. The 1972 image shows the highway slicing across the desert's sand dunes. The other images show a widened corridor, the brighter tones that follow the highway.

The building of roads and streets is a visible sign of urban expansion in Landsat images. Two new freeway interchanges show up in southwestern Sioux Falls in the 1995 and 1997 images. Once retail began expanding, new interchanges were needed to access the shopping and dining areas. After these new interchanges were built, additional development soon followed.

In new residential neighborhoods, the street patterns appear white-blue in color at first. These areas gradually change to a mottled blue-red as time goes on. Red indicates plant growth—in these neighborhoods, as trees mature, they begin to obscure the streets that were once clearly visible. As new residential areas expand west and south, you can see the new neighborhoods appear bright white-blue in color because trees are still too small to block the satellite’s view of the homes and streets.

A curious line appears in only the 2016 image, starting near the upper left, curving southeast, then bending straight east. This is the path of the Dakota Access Pipeline, which carries oil from the Bakken formation of North Dakota to Illinois. The line is not in the 2018 image as cropland or other vegetation regrew over it. The brightest part of the pipeline dig is on the west side of the image, near another bright spot, which is the regional landfill.

Devils Lake in northeastern North Dakota is a closed basin lake. Located at the lowest point within its basin, Devils Lake has no outlet. The result is that the lake is more prone to significant lake level variations. Lately, it has only been rising.

A USGS North Dakota Water Science Center graph shows the lake’s level has been higher in the past two decades than ever recorded.

The frozen tundra of northern Canada might not be the first place you’d look for a diamond mine. Diamonds are created under intense heat and pressure, yet here they are being mined in a cold, icy region.

These mines are located about 320 kilometers (200 miles) northeast of Yellowknife and just 200 kilometers (124 miles) south of the Arctic Circle. The tundra here consists of boulder fields, wetlands, and over 8,000 lakes with interconnecting streams. The lakes are visible in the images as the numerous dark shapes.

The two diamond mines visible in these images are Ekati and Diavik, both located in Northwest Territories, Canada. Ekati is in the northern part of the images. Diavik is in the southern portion and extends into the lake in the series of images.

Most of the year, these mines are accessible only by air. An ice road is open for about 10 weeks of the year during winter. No other roads reach the mines.

Production in the Diavik Mine began in January 2003. By 2013, Diavik had produced 84 million carats.

In this time series, you will notice something different about the mine pits of Diavik. The diamond ore is under the lake, so the pits were built in the lake. To protect the water of Lac de Gras, a dike was built before digging the pit.

Construction is a challenge in this remote location with a short construction season. The dikes had to be completed when the lake was not frozen—only about a 4-month period. The first dike was made watertight in 2002 and was pumped dry 3 months later. Silty water was cleaned before being sent back to the lake. A smaller dike was completed in 2006. The dikes allow safe mining in the open pits.

In September 2012, Diavik transitioned from an open-pit mine to an underground mine. More engineering and construction feats were needed for this change. Ventilation systems, pump stations, 12 miles of tunnels, vertical tunnels for ventilation and water removal, and other rooms make the underground mining possible. Diavik is expected to operate through 2023.

Diavik has a private airstrip of its own. The 1,600-meter (1-mile) long runway can accommodate Boeing 737s. It’s visible in the images as the straight line north of the mining operations.

Doha, the capital of Qatar, used to be a small fishing and pearl diving village. It’s now Qatar’s largest city with skyscrapers and a fast-growing urban area. Doha is investing heavily in education, culture, and sports. The vast majority of Qatar’s population lives in metropolitan Doha.

Oil was discovered in Qatar in 1937, and development began after World War II. Modern urbanization soon followed, and the country now has the highest per capita income in the world.

After winning the bid to host the 2022 FIFA World Cup, Doha had a new motivation to develop its infrastructure. The Qatar government invested in new stadiums and improved public transportation systems.

The urban growth in the PRD is vast. There are no longer any clear urban centers—a different growth trajectory from other large cities in China such as Beijing and Shanghai that have grown around defined historical urban centers.

Buildings and paved surfaces replaced vegetation at a rapid pace over the past three decades. Housing, factories, and the highway system all increased mostly at the expense of farmland.

In the early images of this series, cities are pink areas, separate from one another, among the green forested and agricultural areas. The largest city in this set of images is Dongguan. A noticeable change by the 1994 image is a road network beginning to connect those cities. The urban area soon begins filling in the former agricultural areas and surrounds the hilly forested areas.

In the southern part of the images, blue rectangles are aquaculture, and they are gradually pushed toward the coast by the expanding urban areas.

The city of Dongying is prominent in the 2010 image. Its current population is over 1.2 million. But you won’t find the city in the 1976 or 1979 images because it isn’t there. Dongying was established in 1983 with the opening of an oilfield on the northern delta.

Also noticeable in the time series images is the expansion of salt and shrimp farms, displayed by the dark geometric shapes along the coast. These farms were built on what were once tidal flats, a muddy coast that served as a buffer against storm erosion. Extensive development has degraded the tidal flats, resulting in increased coastal erosion.

The aquaculture development on the delta can have positive effects. While many of the shapes seen in the images are salt fields, many are shrimp farms that have recently moved toward culturing different seafood such as sea cucumber and crabs. These species have a lower carbon footprint, and shellfish also help clean the coastal waters. Another species beginning to be farmed is algae, which are at the very bottom of the food chain. Algae, often used as a nutritional supplement, are great at sequestering carbon dioxide from the atmosphere.

The rapid population growth in this area puts pressure on water resources and on the land, which has to grow increasing amounts of food. The region will need to plan carefully for the growth that accompanies economic development.

About 5 million tourists visit Dubai every year and they have plenty to see and do. To attract tourists, Dubai developed the world’s fastest roller coaster, the world’s tallest building, and the world’s largest shopping mall. It also built fancy hotels, beaches, and even a huge indoor ski resort.

In the first image of this series, desert fills much of the image. As Dubai expands, roads, buildings, and irrigated fields spread out over the desert. But the most prominent project in Dubai, and an impressive engineering feat, is the artificial islands built off its coast. The islands were built from sand dredged from the sea floor. Rock breakwaters protect them from erosion. These Landsat images show the rapid and impressive development of these islands.

The United Arab Emirates (UAE) holds about 6% of the world’s total oil reserves. The oil cannot last forever, so Dubai is thinking of the future. The fast-growing city, and most populous in the UAE, is diversifying its economic base by becoming a luxury tourist destination.

Landsat can track the city’s urban growth, along with numerous other types of landscape changes.

(Black stripes run through some of the images because of the Scan Line Corrector failure on Landsat 7 in May 2003.)

At the southern end of Bahrain is a sight that can only really be appreciated from far above. The first residents moved to this group of artificial islands in 2009. Designed for residential living and tourism, the complex includes six atoll-like islands that surround five fish-shaped islands.

These images reveal additional projects that are in progress throughout the region. The Crescent is the center and will be a commercial hub, with apartments, offices, restaurants, shopping, and a 600-room hotel. The Durrat Marina is under construction to the north and will provide space for 400 boats and yachts. A planned golf course will be built amid 2,220 luxury residential villas and apartments and take up about 90 hectares.

When completed, the Durrat Al Bahrain will be able to accommodate 60,000 residents. Construction of the islands can be seen in the 2003 Landsat image. Many of the atolls have been developed. Look carefully at the 2014 and 2015 images. In just a matter of months, development began on the two southernmost fish-shaped islands. A 2023 image shows a more current view.

(Black stripes run through the 2006 images because of the Scan Line Corrector failure on Landsat 7 in May 2003.)

Even with these reservoirs, dry lakebeds surrounding Zabol are problematic. A “120-day wind” blows in this region. These persistent spring and summer winds can cause dust storms in and around Zabol.

Zabol reports dozens of dust storms every year. Clouds of dust from the lakebed cause breathing problems and can spread respiratory diseases. Many villages in the region have been abandoned.

The August 2000 image shows an extensive dust storm blowing sediment off the dry lakebed toward the south. The dust plumes obscure most land features and reach to Lake Gowd-e Zareh and beyond.

The view of this region from Landsat is so fascinating, it’s the subject of two Earth As Art images. These and all Earth As Art images can be downloaded for free from the EROS Image Gallery.

Eerie Cloud Shadows

Geometric Desert

On the east side of Sioux Falls, cropland continues to give way to developed land. Many U.S. cities have grown with a similar pattern—people moving to suburbs instead of to the central part of cities. Suburbs changed from bedroom communities to having their own focal points for retail and service industries. Sioux Falls reflects this phenomenon at a smaller scale—both retail and residential development expand into these suburban-type areas.

Note that the land is cleared first, noticeable as a pale smudge, and then street patterns emerge. Larger white blocks in the images are retail establishments, often with parking lots surrounding them.

Retail development covers former farmland along a new highway called Veterans Parkway. The road eventually lengthens to meet up with Interstate 90 to the north, a strong hint at where more growth is planned.

Northeast of this Sioux Falls expansion is the city of Brandon. There is starting to be less distance between Sioux Falls and Brandon. Since 1970, Brandon’s population has grown by over 500%, greatly outpacing the Sioux Falls metro population rate of growth during this time.

Just west of Clay City, there is a large, nearly square-shaped area of floodwater in the 2008 flood image. It covers about 2,200 acres. The fact that this area became inundated indicates that it is low lying land. It’s possible that during the flood, water flowed from the nearby Eel River through a breach. The 2007 image shows this area as cropland, which is commonly low and flat. Roads, built up above ground level, could be causing the straight lines that appear around the water in the flood image.

Interestingly, this spot was once an artificial reservoir, called the Splunge Creek Reservoir, that formed in the 1800s to supply water to the Wabash-Erie Canal, which no longer exists.

Ekati is Canada’s first diamond mine. Diamond ore bodies are called kimberlite pipes. These carrot-shaped pipes are the roots of ancient small volcanoes. Diamond-bearing kimberlite was discovered at Ekati in 1991.

Construction of the mine started in 1997 and it officially opened in October 1998. By 2011, the Ekati mine had produced 50 million carats of diamonds.

Ekati is the name the Tlicho people gave this area. It means “fat lake,” a reference to white quartz in the rock on the shore of Lac de Gras. The quartz looks like marbled caribou fat. Lac de Gras is the large lake south of the mines.

You can see the mining operations expanding in this series of images. The Ekati mine includes open-pit mines in different locations. In the lower right is the Misery pit. It’s connected to the main base of operations by a road, visible as the curving pink or white line.

Ekati has its own airport that’s used year-round. That’s how employees get there. The runway is visible as a straight line just south of where the first open pits begin appearing.

The company that runs the Ekati mine, Dominion Diamond Ekati Corporation, monitors the air, water, and wildlife in the area. They are already planning ahead for the eventual closure of the mine and land reclamation.

These images show the vicinity of the Elburz Mountains in northern Iran. Tehran lies in the south, and the Caspian Sea is to the north.

The Elburz Mountains run parallel to the southern coast of the Caspian Sea, and these mountains act as a barrier to rain clouds moving southward; as the clouds rise in altitude to cross the mountains they drop their moisture. This abundant rainfall supports a heavy rainforest (the bright red area) on the northern slopes. The valley to the south receives little precipitation because of this rain-shadow effect of the mountains.

Meanwhile, at the summit of Kīlauea, the Halema‘uma‘u crater and surrounding caldera floor subsided throughout the summer of 2018. Kīlauea has something like a plumbing system connecting Halema‘uma‘u crater at the summit to the lower flanks of the volcano. The collapse at Halema‘uma‘u suggests the underlying magma reservoir largely drained into the lower East Rift Zone to feed the lava flows.

Magma draining from the summit hints at the possibility of a quiet interlude at Kīlauea for several years. While April 30, 2018, marked the beginning of the recent lava flow event, it also marked the end of the continuous eruptive activity at Pu‘u ‘Ō‘ō that started in 1983.

Although lava flowed from the East Rift Zone and devastated the Leilani Estates neighborhood, the April 30 collapse of Pu‘u ‘Ō‘ō crater left this eruption site devoid of lava. Since lava did not return to the crater after August 4, the USGS has said the Pu‘u ‘Ō‘ō eruption is over.

However, the USGS Volcano Hazards Program says Kīlauea is still active and will erupt again. Volcano hazards in the area remain the same. Based on historical data, it’s unlikely that lava will erupt again from Pu‘u ‘Ō‘ō, but the East Rift Zone still has magma underneath, and it will erupt again through another vent. It may take several years for enough magma to accumulate again, but Kīlauea and the East Rift Zone remain very active.

The USGS Hawaiian Volcano Observatory created a geonarrative to summarize the history of Kilauea eruptions and the 2018 lava flows.

The environmental implications of the shrimp farm expansion are potentially far-reaching.

• Fish meal fed to the shrimp can contaminate the environment
• Antibiotics used on the shrimp are associated with human health problems
• Misuse of antibiotics and other chemicals can affect groundwater quality
• Mangrove forests are lost

The loss of the mangrove forests leads to further problems.

• Increased risk of inland flooding
• Degraded water quality can reduce catches by off-shore commercial fishers
• A carbon sink area can become a carbon source

Images from Europe's Copernicus Sentinel-2 satellites show a bit more detail than Landsat. These close-up views of Shiyan show the industrial development and land clearing at 10-meter resolution. Blue-topped rooftops are buildings for industry; light tan spots are leveled land.

The hills that are being flattened vary in height from 100 to 150 meters. The material used to level the hills is used to fill valleys. However, building on this infill might not be best for urban construction. The soft soil from the infill subsides easily and is prone to landslides.

Other environmental problems are cropping up based on this land leveling. The process of moving this much material throws dust particles into the air. Changing hills to plains has caused soil erosion, which adds sediment to local water sources. Shiyan is near the headwaters of the South-North Water Transfer Project, a huge project that diverts water to northern China. The sediments can end up in waterways, polluting the water. Furthermore, it can take years for the flattened ground base to be stable enough for building.

After the eruption, many areas near the volcano were stripped of vegetation. The series of images reveals the regrowth of vegetation, but it progressed at different rates. The eastern side recovered the fastest, where the area was mainly affected by falling ash. Wind and rain removed the ash, and most areas on this eastern side recovered to almost pre-eruption levels in about 7 years.

The mountain’s western side experienced the worst of the pyroclastic flows, causing regrowth to be slower and more variable. In fact, some areas are still bare.

A remarkable feature of the series of images, even in the most recent images, is that mudflows can still be seen trailing away from the mountain’s summit more than 30 years after the eruption. Runoff from monsoon rains and typhoons continued to erode and redistribute the pyroclastic deposits years after the 1991 eruption.

Another change visible at this scale is the summit itself. The eruption caused the summit to collapse into a caldera about 2.5 kilometers wide. Water has collected in the crater to form a small lake.

Landsat’s infrared bands set up a clear contrast between vegetation and lahar deposits. The images make it clear that the lahar hazards continued, and many occurred in inaccessible areas. Vegetation shows up as bright green, while the sediment and bare ground from lahars is pink. It also shows the progression of the revegetated areas on the mountain’s slopes.

This progression is aided by additional scenes from Terra’s ASTER sensor. ASTER uses similar infrared bands to Landsat, and its 15-meter resolution reveals slightly more detail than Landsat’s 30-meter resolution.

Isolated in Chile’s northern Atacama Desert, the open-pit Escondida Mine is the world’s largest source of copper.

Escondida means “hidden” in Spanish, and hidden it was. The copper ore was buried under hundreds of meters of rock. The only way it was found was by drilling along a line of other known copper finds that stretched hundreds of kilometers.

Copper represents a substantial part of Chile’s economy. In 2013, copper mine production was valued at just over $30 billion. Chile is the world’s leading producer of copper, accounting for nearly 32% of world copper production.

With these water use maps, land managers and farmers can tell which crops use the most, or least, water at the field scale. From this, they can determine whether water could be used more efficiently. At the basin scale, large-area maps can be used to evaluate aquifer depletion and quantify groundwater pumping; or resolve water rights allocation disputes.

The accompanying pair of seasonal ET maps (May–September) shows crop water use in the San Joaquin Valley in 1990 and in 2014. The colors correspond to millimeters of water returned to the atmosphere through ET. Fields that are green and blue show the highest ET values. Relatively more water has been used on those irrigated fields. Orange hues are areas that have very little ET, such as sparsely vegetated desert.

Comparing the maps reveals changes in irrigation patterns during this period. Notice, for example, that water use intensified in many places (increase in blue areas) and some irrigated lands (green in 1990) transitioned out of agricultural production (reddish brown) by 2014.

These water use maps can show not just seasonal ET but water used in a single day, or even over the course of decades thanks to the extensive Landsat archive. View the .gif animation below that shows an annual ET map for every year from 1984 to 2014. This map series shows flooding events around Tulare Lake Bed in 1984 and 1997.

Accurate information on water availability and usage is necessary for planning sustainable use of water, particularly in an arid region like the southwestern United States. The study done for the San Joaquin Valley can become the basis for planning, monitoring, and assessing water use across the country. These maps can help farmers and land managers optimize and conserve water resources.

An expanded Landsat acquisition plan started collecting more satellite imagery during polar night or twilight. The plan, called the Landsat Extended Acquisition of the Poles (LEAP), defines 306 additional path/rows for Antarctica, Greenland, and Arctic Sea regions.

Studies of Petermann Glacier can benefit from this additional imagery. Changes there and at other Arctic and Antarctic locations can be studied in more detail with LEAP collected data.

Typically, Landsat imagery has not been acquired for far northern latitudes from late September to mid-March. And in Antarctica, imagery is limited from March to September. But ice shelves can breakup even in the dark wintertime or polar twilight. 

In an Eyes on Earth podcast, USGS Scientist Chris Crawford said, “Extending the ability to observe ice and polar ocean changes in the twilight just simply increases the probability of capturing these major calving events, or even being able to see the preconditioning that's happening that will lead to a major rare event.” He added, “We expect that this will unleash new science applications and then more routine climate monitoring of the polar regions.”

The Landsat images displayed here show a winter, dark image and a summer, daytime image, both from Landsat 9. The winter image displays data from the Thermal Infrared Sensor, acquired when the sun was below the horizon. Darker areas are relatively colder than bright areas. The natural color image was acquired in August during the day.

One new building project that exemplifies some of these trends is visible southeast of Beijing. Fangzhuang is a new city of 78,000 where in 1984 only 1,000 people lived in agricultural villages just outside the Outer City. In the 1977 image, agriculture, represented by red, dominates the area. By 2022, those lands have been swallowed up by development.

Fangzhuang includes condominiums, 3-story apartment buildings, schools, parks, shops, and a community center. Such prestigious work-units as the Ministry of Foreign Affairs have bought blocks of apartments, and since 1994 some foreigners have moved in. Operations such as health care, day care, and garbage collection are still managed by socialist-style committees of residents.

The aerial photo from 1952 is black and white and doesn’t have the infrared imaging capability of Landsat, but it has something that Landsat doesn’t—very high resolution.

It’s possible to locate trees and buildings in this image. Zooming in to an area near the lake is a location that is cultivated cropland. The sharp corners mark the different fields.

Land here is divided into sections of 1 square mile. These extreme closeups show an area of land covering approximately six sections. This area shows three sections across and two sections high.

A closer look shows farm buildings, with a shelterbelt of trees beside them.

Later Landsat images reveal that those fields and structures are underwater.

* = Location of farm structures shown in the aerial photo closeup.

These images show the Filchner Ice Shelf on the coast of Antarctica that faces the Atlantic Ocean. In the austral winter of 1986, the front edge of the Filchner Ice Shelf broke off into the sea, forming three large icebergs. This was a major, long-awaited calving.

Most images in Earthshots are in “false color”; they are red/green/blue composites, representing three bands of Landsat data. These images of the Filchner Ice Shelf, however, represent only one band of near-infrared reflection, so they are grayscale.

An ice shelf is a huge sheet of ice, connected to land but extending out into the ocean. Ice shelves develop mainly from glaciers flowing slowly downhill toward the ocean. “Upstream,” the ice shelf rests on land, but “downstream,” the ice shelf extends out onto and into the ocean, mostly below sea level.

The Filchner-Ronne Ice Shelf is by volume the largest ice shelf on Earth. It is really one ice shelf, nominally divided by Berkner Island.

Ice shelves are part of a cycle. Winds carry water (as clouds) to Antarctica, where it falls as snow, compacts into ice, flows slowly as glaciers into ice shelves, and then slowly progresses to the ocean, where chunks break off and are carried away by ocean and wind currents. These chunks are icebergs; the birth of icebergs (from glaciers, ice shelves, or larger icebergs) is called calving.

It is widely known that most of an iceberg lies under water; this is also true of ice shelves. When a large piece of ice shelf calves into the ocean, it does not drop and splash down into the water, because the front of the ice shelf was already floating on water. In fact, the ocean’s tides lift and drop the ice shelf every day; this is called hinging, and the place where the ice shelf connects to the “shoreline” bedrock is called the hinge-line, since the outer shelf swings up and down from it.

German scientists learned that the Filchner-Ronne Ice Shelf is two-layered. The top 150 m of ice came from snow and glaciers, but the bottom 80 m of ice came from the water below. This bottom layer is clear and bubble-free. The top layer is hard but snowy and bubbly. These bubbles (or “voids”) allow scientists to study atmospheric gasses trapped in the voids, by coring the ice.

Antarctica has 90% of the world’s ice. Scientists are very interested in the net gain/loss of this ice mass because of its implications for world climate and sea level.

Fire scars of varying size show up in these Landsat images from the Athabasca oil sands region of northwestern Alberta, Canada. These fire scars show up as red or maroon against the green vegetation. Fires are a part of life in the boreal forest, but in 2016, an unusually intense forest fire, fueled by dry conditions and high winds, devastated the region.

The 80,000 residents of Fort McMurray were forced to evacuate, the largest evacuation on record in Canada. The fire destroyed 2,400 structures in and around Fort McMurray, and at least another 500 were damaged. Many structures still standing suffered smoke damage.

At its peak, the fire moved 30 to 40 meters (98 to 131 feet) per minute. It burned a total of 589,552 hectares (nearly 1.5 million acres), and part of that area is shown in the series of images. Using shortwave infrared (SWIR) and near-infrared (NIR) bands to help penetrate clouds and smoke and create false-color images, Landsat shows the burned area in dark red. It’s clear that Fort McMurray was quickly surrounded by the blaze.

Landsat’s infrared sensors are valuable for producing burn severity maps and other products quickly after images are acquired.

In these Landsat images, the old forest is dark green. In the 1987 image, this forest is occasionally broken up by lighter green grassy meadows or grassy plains. Geyser fields are pale blue and white. In a few places, a pink tinge may indicate old burn scars or dormant plants.

The August 23, 1988, image was acquired when many fires were active. Smoke obscures some of the land, showing up as blue because the image uses infrared wavelengths of light. Land just burned is dark red. Lighter red patches are less severely burned.

The band combination of shortwave infrared, near-infrared, and visible green highlights the changes in vegetation caused by the fires and recovery. Dark red burn scars fade over time as vegetation recovers. Grasses and wildflowers grow out of the ashes, and young trees begin to take root and grow. These light green areas start replacing the red and pink from the burn scar.

As intense as the fires were, studies showed that less than 1 percent of soils were heated enough to sterilize the soil to kill belowground plant seeds and roots. Grass actually prospered in the rich soil immediately after the fires because of the release of nutrients and the decrease in shading from shrubs and trees. Less competition with other plants for resources also allowed grass to flourish.

Even though grass flourished and saplings soon emerged, the recovery is gradual. Even in the 2011 and later images, the burned areas from 1988 can still be seen. The high elevation in this area causes a short growing season. With the hot, dry summers and cold, harsh winters, the forest will not return to its prefire conditions for decades. But recovery will continue.

A few new fires show up in the later images to show that fire continues to be a part of the Yellowstone wilderness.

Southeast Australia has a history of severe fire problems, with some historic deadly fires such as the Ash Wednesday fire of 1983, and lesser fires almost every year. The state of Victoria averages about 19 large fires (over 1,000 hectares) per year. These fires are often fast like grassfire but more intense. The winter rains that benefit wheat farming also aid the buildup of plant matter, which becomes highly combustible during the dry summers. Perhaps 60% of the fires in Wyperfeld are started by lightning, with the rest from various human accidents and purposes, including fuel reduction. Since the 1950s, Australians have systematically set controlled fires to reduce the risk of dangerous fires later. Wyperfeld staff currently set fuel-reduction fires along the park’s edges but fight all accidental fires, as required by law.

These fires kill individuals, but communities of living things survive. Studies elsewhere in Victoria indicate that 2–4 years after a fire, the forest floor is again littered with small twigs and leaves, the habitat for many small animals. There are more plant species in the area than before the fire, though frequent burning certainly can kill out some species. Forest studies show that different post-fire stages favor different species; mice do well right after a fire, for example, but some birds do better in long-unburned or intermediate areas. Now that habitat is restricted to “islands” of parkland, there is danger of an entire park being burned out, with no adjacent communities to recolonize the burned areas.

The Landsat images here show a stark change from unburned bush in 1977 to huge burn scars in the later images. The age of the scars can be estimated by their color; old scars are almost as dark as the bush, half-regrown scars are only pink, and the newest scars are very bright.

In 1947, Copenhagen established the Five Finger Plan. The plan for the city’s growth designated five corridors of urban development, which were along railway lines to provide convenient transportation to Copenhagen’s business district in the central part of the city. Planned suburbs were to be built along these corridors and linked together like beads on a string.

The development plan resembles a hand with five fingers stretching out away from the city center. The plan allowed for controlled urban growth while leaving space open for recreation and agriculture. These green spaces were to occupy the land between the fingers.

As the series of images shows, the five fingers and hand shape are indeed vaguely recognizable. In these false-color images, the developed areas are shades of purple. Buildings and pavement are very reflective. On the other hand, water reflects very little sunlight, so it shows up as black.

The cut flower industry can be seen in Landsat images near the lake in both outdoor fields and in glass greenhouses. The greenhouses are silvery in these views. The fields are a mix of green, tan, and purple. Tan and pink are fallow fields, and the green fields have growing plants. These fields and greenhouses have expanded over the time frame covered by these images.

The flowers grown in the region include roses, carnations, statice, alstromeria, lilies, and hypericum.

Since 1986, the nature of agriculture around Lake Naivasha has changed from mostly ranching to floriculture. The flower industry especially has led to increased population in Naivasha and the surrounding area. From 1969 to 2009, the population of the Naivasha Division increased more than 750%.

The flower farms use a lot of water from the lake and send nutrients and chemicals back to the lake. In addition, the increased population is placing more pressure on the freshwater resources in the region. As a result, the chemistry of the lake is changing. More blue-green algae and tiny crustaceans are appearing in the lake, which are food for flamingoes. The pink birds usually flock to lakes salty enough to find this food, so it was unusual to see them in abundance at Lake Naivasha.

Floriculture began around Lake Naivasha in the early 1980s. During the 1990s and early 2000s, the amount of land dedicated to floriculture rapidly increased, changing from grassland and shrubland to flower farming. The increased water use led to a drop in the water level of the lake and an increase in farm runoff laden with agro-chemicals.

The water that is used to grow these crops dates back to the last ice age. Known as fossil water, it has been buried deep underground for about 20,000 years.

The agricultural fields are round because of a technique called center-pivot irrigation. Sprinkler systems move around a central pivot to water the field. The technique provides better control of water and fertilizer use, which is important where water can evaporate quickly. The fields shown in these close-ups vary in size. The largest circles are about 1 kilometer across.

The drawback with this technique is that water in these aquifers is not recharged. Rainfall here averages only 100 to 200 millimeters per year, and that makes the groundwater in the area a nonrenewable resource.

The amount of water stored in the aquifer under the desert ranges from 252 to 870 cubic kilometers. Hydrologists believe it will only be economical to pump this groundwater for about another 50 years.

Groundwater irrigation here is only possible because of another nonrenewable resource—oil. The Saudi government used income from the sale of oil to fund these irrigation systems. Saudi Arabia spent billions of dollars developing agriculture in the last 15 years of the 20th century. In 2008, the Saudi government began phasing out domestic wheat production. By 2016, the country ended its domestic wheat production program because of concerns about the depletion of water reserves. However, since the announcement to phase out wheat, some farmers have begun growing forage crops to feed livestock, a less efficient use of water.

Besides some recovery from the 1988 fires on the west side of Yellowstone Lake, this series of images shows the effects of another fire.

Frank Island is the largest island in Yellowstone Lake. The island was set up as a protected area for ospreys that nest on the island. The public is not allowed on the island during the summer. Only a small picnic area on the southeast point is open for visitor use.

On August 8, 2003, lightning struck Frank Island. An inferno quickly engulfed nearly all of the old growth trees. Most of the forest on the island burned.

The first image in this series is from one week before the lightning strike that started the fire. The island appears deep green in the middle of the lake. In the other images, virtually no vegetation remains on the island. The green was replaced by pink, which indicates barren ground.

Many projects were headed by loyal party leaders with no technical skills, which is another reason the canals were not more effective. Teachers, technicians, and other skilled (usually urban) professionals—hated by the Khmer Rouge as corrupting urban influences—were executed. Thus, primarily inexperienced and unskilled citizens, including the evacuated city-dwellers, were forced to work in the countryside growing rice and building these irrigation works, with rigid work quotas and hard, slave-like conditions. The lack of experience led to inefficient canals that occasionally collapsed in the rain.

Not only were the canals poorly constructed, but they also were built in straight lines, regularly spaced, at right angles along the 1-km gridlines of their military maps, ignoring hills, villages, and other topography. Some claim that many of the canals actually did more harm than good, disrupting natural water supplies and encouraging erosion. This pattern can be seen in most of these images. In more recent years, the irrigation system built during the Khmer Rouge regime is much less defined in satellite imagery.

It appears in the images that each district had to dig a certain amount of ditches, whether needed or not. Indeed, workers had rigid daily quotas, so that some finished early and some could never finish. There were strict decisions about which varieties of rice were acceptable, diminishing the diversity of varieties which had adapted to local conditions.

Though it is likely that by the end of the Khmer Rouge regime canal construction expertise had improved, the post-Khmer Rouge government had to devote considerable resources to repairing irrigation works. One official said 80% of the projects had been poorly constructed, though it varied by region.

Although many of the canals were poorly built, some of them can still be used. The Cambodian Prime Minister Hun Sen started supporting the re-digging of the canals in 2005, and now that the people who are rebuilding them are no longer under the Khmer Rouge, they get paid a small amount, and the crops that are harvested aren't taken away by the government.

These Landsat images feature the significant growth in the use of center-pivot irrigation—essentially enormous sprinkler systems—in Kansas between 1972 and 2021. The Arkansas River flows east just south of Garden City in southwestern Kansas. From 1972 to 1990, Garden City's population grew from about 15,000 to about 24,000. The town's population as recorded by the 2020 Census stood at 28,151.

Much of the former shortgrass prairie of western Kansas is now irrigated cropland. Common crops in this area are corn, wheat, and sorghum. Red areas in the images are healthy vegetation. Light-colored cultivated fields in the images are fallow or recently harvested wheat fields.

These images show center-pivot irrigation systems (the small circles) multiplying between 1972 and 1988. From 1969 to 1987, irrigated acreage in Kansas increased by 62%, from 1.5 million acres to 2.4 million acres. In the five years from 1984 to 1988, Kansas farms with center-pivot irrigation systems increased 19%, from 2,630 farms to 3,122 farms.

This area uses irrigation water from the High Plains Aquifer—also known as the Ogallala Aquifer—one of the world's largest aquifers, which underlies an area from Wyoming to Texas. Landsat images are useful for measuring irrigated crop acreage, a key component of modeling aquifer response to changes in water use. Landsat is also used to monitor the depletion of the aquifer, which is affected by not only the irrigation but also drought.

At nearly 244 meters tall, Gibe III is Africa’s tallest dam and the continent’s third largest hydroelectric plant. Its estimated production capacity is 6,500 GWh a year.

The first large dam on the Omo River, Gibe III takes its name from a tributary of the Omo, the Gibe River, on which two smaller dams were previously built. The Gibe I hydroelectric turbine was installed in 2004, and Gibe II in 2010. Gibe IV and Gibe V are planned to be built on the Omo downstream of Gibe III.

Construction of Gibe III began in 2006. The reservoir, now 155 kilometers long, began filling in February 2015. The reservoir fills the entire canyon that the river flowed through. The dam began generating electricity later in 2015 and was fully commissioned in December 2016.

The electricity generated by the dam is also exported to Kenya and other countries, bringing in hundreds of millions of dollars of revenue for Ethiopia. Electricity can also be delivered to Ethiopia’s rural areas, where just 26.5% of the population had access to electricity in 2015.

Located 450 kilometers south of the capital Addis Ababa, the dam is also used to regulate floodwater and provide water for irrigation. However, the dam ended the natural annual flooding that brought nutrients to the banks of the Omo River. The lack of floods makes it more difficult to grow food there.

An artificial regulated flow through the dam was intended to mimic this natural flood pulse. But the dam traps sediment, so even with regulated flow through the dam, there will still be impacts on wildlife and farming because of the reduced nutrients from this sediment.

Because the Omo River accounts for 90% of the inflows to Lake Turkana in Kenya, there are major effects on the water levels and water quality of that lake, especially now that the water is used for other purposes such as large-scale irrigation. Furthermore, the reduced flow from the Omo causes increased salinity in Lake Turkana, which can affect some fish species.

The great thing about hydropower is that it’s a renewable nonpolluting source of power. Once it’s up and running, operation costs are relatively low, and the energy supply is very reliable.

In the United States, most of the best locations for hydropower have already been taken (such as Hoover Dam near Las Vegas and the Glen Canyon Dam). Other countries are starting large hydro projects to further development and provide reliable power for more communities. In Ethiopia, for example, a series of large dams on the Omo River provide electricity for the country and enough to export to neighboring countries. They also provide irrigation water for large-scale agriculture.

Hydropower projects of this scale often come with downsides as well.

Large hydropower projects can have a massive effect on the landscape. Reservoirs can change local ecosystems and fish habitat, and sometimes displace large populations of people. In the case of the Gibe III dam, the rapid changes could have substantial effects on the people living downstream who depend on the river’s regular pulse floods for farming and fishing.

Gibe III is the third hydropower plant on the Omo River, what they’re calling a hydroelectric cascade.

The Omo River has a unique geo-political dynamic. The river is entirely contained within Ethiopia’s borders. However, the river empties into Lake Turkana, which lies almost entirely within neighboring Kenya to the south.

Another forest reserve called Gilli Gilli lies directly south of Okomu. Gilli Gilli has experienced less deforestation than Okomu—limited to smaller areas of degradation on its northern side. The low rate of degradation in Gilli Gilli could be because few settlements are located near it. This area is more inaccessible than Okomu.

In Okomu, a farming system called Taungya was introduced in 1945. The plan allocated parts of the reserve to food crops. Trees were required to be planted on the same farm plots and would be allowed to be harvested as timber. In Okomu, however, migrant farmers often did not plant trees. In Gilli Gilli, however, the Taungya system was not introduced.

The Landsat images do show moderate deforestation in its northern part, gradually spreading toward the southeast. However, this area’s inaccessibility has spared it from large-scale forest degradation.

A stable glacier advances a little in the winter and retreats the same amount in the summer. Bear Glacier likely did this and gradually built up a terminal moraine. (A moraine is a buildup of glacial material, and a terminal moraine is one that is built up at the end of the glacier.)

During the last 100 years in Alaska, the annual average temperature has increased by about twice the global annual average temperature change. A temperature increase like this can change the regular pattern of glacial advance and retreat.

Between 1950 and the 1990s, Bear Glacier retreated 1.55 kilometers (1 mile). Small icebergs were calving into a lagoon that had developed. By 2004, the glacier’s floating terminus calved, causing an additional 2 kilometers (1.25 miles) of retreat. Between 2000 and 2007, the terminus retreated another 3.5 kilometers (2 miles). Large icebergs now float in the lagoon, visible in the Landsat images as light blue spots in the water.

USGS uses repeat photography of glaciers to quantify changes in glaciers over time. Repeat photography is a technique in which a historical photograph and a modern photograph, both having the same field of view, are compared.

For example, oblique aerial photographs of Bear Glacier were taken facing north and show glacial retreat along with icebergs floating in Bear Glacier Lagoon.

Photographs taken from the ground look north and were from the same location on the eastern part of the terminus of Bear Glacier. In the 96 years between photographs, Bear Glacier has retreated more than 3 kilometers (1.9 miles) and thinned by as much as 200 meters (656 feet). Only a very small part of Bear Glacier is visible from this location today, and the terminus is obscured by the trees.

Glen Canyon Dam near Page, Arizona, creates Lake Powell. The 710-foot-high dam was completed on September 13, 1963, about 9 years before the first clear Landsat 1 images were acquired. The dam also generates electricity. From 1980 to 2013, its average annual gross electricity generation was about 5 billion kwh. (kwh = kilawatt-hours, a measure of a power station’s electricity output.) Its electricity generation varies based on the amount of water that flows into the lake, which is influenced by precipitation.

In the Landsat series of images shown here, we begin with 1972 when the lake was still filling. In 1984, the lake was at one of its highest water levels.

Near the dam is the city of Page, Arizona, which began in 1957 as a housing camp for workers building the dam. Page is now a major resort area. Its 2023 population was 7,320.

At various marinas on the lake, tourists can rent houseboats and other recreational watercraft. Wahweap is the largest marina on Lake Powell. This marina needs to move based on the lake’s water level. Antelope Point is the newest marina on Lake Powell, established in 2004.

Antelope Island is in the center of these images. It looks a lot less like an island in the later low water level images. The National Park Service dug a channel on the island’s north end called Castle Rock Pass. Even though it begins to look more like a peninsula by the 2005 image, it is still called Antelope Island. The channel around the north side of the island is navigable when the lake’s water level is 3,620 feet or higher.

Researchers from the University of Maryland and USGS have mapped changes in forests globally from 2000 to 2013. The maps displayed here are from that database and are paired with a corresponding Landsat image.

The study defined trees as all vegetation taller than 5 meters. In the forest change map, green indicates forest extent, and red is forest loss during the period 2000–2013. Any blue that appears is forest gained during that time period. Black is land that was non-forest during the time period.

The study used data from over 650,000 Landsat scenes and used 143 billion 30-meter Landsat pixels.

Other mines also continue to expand, even in the Landsat era. The Hull-Rust-Mahoning Mine near Hibbing is one of the biggest mines in the world. Some call it the “Grand Canyon of the North.”

Rather than a natural wonder, the 535-foot-deep mine is another huge open pit gouged into the Mesabi Range and expanded over the decades. In the Landsat images, it’s still the tailings basin that stands out and takes up more land area. The mine itself is between the tailings basin and the city of Hibbing. Both the basin and the mine expand during this time series of Landsat images.

Another tailings pond expands farther to the south. This is the Keetac mine and tailings basin.

Another USGS aerial photo shows part of this area pre-Landsat. The Hull-Rust-Mahoning open-pit mine is just north of Hibbing in 1953, but the current tailings basin had not been established yet.

The reservoir behind the largest hydropower plant in Africa has begun filling. Under construction since 2011, the Grand Ethiopian Renaissance Dam (GERD) is 1.1 miles long, 509 feet tall, and spans the Blue Nile River in Ethiopia.

The GERD reservoir is in a deep gorge, so its surface area is relatively small compared to its volume. This means less water will be lost to evaporation than in desert reservoirs. The lake’s capacity is about twice the volume of Lake Mead.

Including the Aswan High Dam in Egypt, which forms Lake Nasser and has the capacity of four times the volume of Lake Mead, two of the world’s largest dams are now on the Nile River system, in two different countries.

The first phase of GERD reservoir filling began in summer 2020. The curved shape southwest of the main dam is referred to as the Saddle Dam, and the reservoir reached it for the first time in 2022.

Landsat imagery may make it look like the lake is filling at a rapid pace, but filling the reservoir is still a gradual process. Filling too quickly could lead to hydrologic water shortages downstream, especially if a drought hits at the time.

Just west of the mining area, a dark green patch of land emerges in the time series of images. This is a cooperative farm called Granja Porcón. The 12,000 hectares of land in the cooperative were originally grassy plains.

The dark green area on the images indicates the effects of an afforestation project. Granja Porcón includes a nursery that produces over a million seedlings per year, and the forest plantations provide wood as a source of income for the local population. Pine species are planted in this location because of their resistance to cold at high elevation.

Tourists can visit and work alongside the residents of the cooperative in day-to-day tasks, such as milking cows or working in the fields.

These images show the dramatic effects of the Great Salt Lake's high water levels in the 1980s. These effects included a great increase in the lake’s area, the opening of the causeway crossing the lake, and the creation of a new evaporation basin west of the lake.

The Great Salt Lake is a terminal lake, with no outlet rivers running to the ocean. Since water leaves the lake only through evaporation, it leaves behind its dissolved minerals, making the lake up to 8 times as salty as seawater.

The lack of outlets also means the lake responds dramatically to change in inflow. Rainy weather beginning in 1982 brought the highest levels in recorded history, peaking in June 1986 and March–April 1987. The lake is shallow for its size—about 70 miles long and 30 miles wide, but only about 40 feet deep. Because the lake basin is so shallowly sloped, extra inflow to the lake makes it rise only slowly, but any rise means a large increase in area. Highways, causeways, and parts of Salt Lake City were flooded or threatened in the 1980s, costing millions of dollars.

Long-term drought and water use led to Great Salt Lake reaching its lowest level on record in November 2022. This low level of the lake can increase dust pollution and reduce mineral extraction, shrimp production, waterfowl habitat, and recreational opportunities.

Landsat imagery shows the lake shrinking from June 2022 to October 2022, then slightly expanding in 2023.

Landsat has been monitoring the lake for over 50 years, and will keep tracking the water level changes.

Other urban centers near Denver are also growing quickly. While the population of the Denver metropolitan area increased by 84% between 1990 and 2022, Greeley, about 40 miles north of Denver, increased by 80.4% in the same time period.

In these false color images, residential areas are a mottled green, with streets, highways, and other infrastructure showing up in purple hues. The brightest green spots are golf courses, parks, and other areas that have growing green grass. Bright green circles and rectangles are farm fields. In fact, just about everything that is green in these images away from the mountains is irrigated.

Other expansion seen in these images is the petroleum and natural gas industry. An increased number of bright spots indicates more oil and gas wells.

These 2021 images show the seasonal progression of the irrigated crops in this area, from around the peak of the growing season to harvest. The August image is at the height of the growing season, and the November image is after many fields have been harvested. The harvested fields are a conspicuous white and not red because the vegetation has been removed.

From 1975 to 2020, Santiago’s population increased from under 3.5 million to just over 7 million. In the late 1970s, housing shortages were increasing, particularly for the poor. In the early 1990s, Santiago’s elites moved to the northeastern suburbs to escape the city center’s increasing congestion, retail, and rural immigrants. The affluent Barrio Alto district is in this quarter, flanked by the Andes and the San Cristobal Hills.

A squatter settlement existed in the Barrio Alto, housing many domestic servants and workers for wealthy households nearby, until the mid-1970s when the government evicted them. A park in place of the squatter settlement was discussed, but instead one of Chile’s largest shopping malls, the Parque Arauco, was built. The former squatters were resettled in public housing in the southeastern part of the metropolitan area.

This followed the pattern of the military government: slum clearance in the city’s center and northeast, with a shift to public housing on the urban fringe, which has been called “the bedroom community of the working poor.” The bulk of metropolitan growth since the World War II has in fact been along the southern edge, where the Central Valley widens and land is relatively cheap. In the mid-1970s, the government bought large tracts of agricultural land and committed its housing resources in this area. The government’s “making neighborhoods healthy” (saneamiento) program has brought services such as water, sewer, and electricity to much of this housing.

A Bit of Trivia

Because Santiago is close to the west coast of South America, it might be hard to tell whether it’s east or west of Los Angeles. But it’s not even close. Santiago is almost straight south of Boston. In fact, because of the angles, the orbit path for this scene (path 233) is one path east of Newfoundland (path 1).

In the 1975 image, the initial clearing for the San Julian settlements is visible along the highway—the pink line heading north-south. Later images show a well-defined 3x3 box pattern with roads connecting them. The United States Agency for International Development (USAID) helped fund new roads along with wells and community center clearing.

In the middle of the two groupings of nucleos is a clearing of a different pattern. This is the Zapito private farm, which is not part of the San Julian colonies.

As an example of how the cities of the region have merged after the 1978 reforms, these images are a closer look at Guangzhou and Foshan. Even in 2000, they were clearly separate cities. The land between them then fills in with urbanization.

The 2017 image shows the appearance of what appear to be several black dots between the two cities. These are high-rise residential buildings. They look a little similar to the fish ponds, but these are a bit smaller, and they are dark because of the shadows they cast on the ground.

Honduras is one of Latin America’s top producers of cultured shrimp. Since the 1980s, vast areas of land have been converted to shrimp farms around the Gulf of Fonseca along the Honduras-Nicaragua border. But there are concerns about the environmental impact of this industry on the gulf’s wetlands.

These images show the location of the USGS Earth Resources Observation and Science (EROS) Center, about 10 miles north of Sioux Falls, South Dakota. On Sunday, July 13, 1997, an unusually severe hailstorm blasted through the area, missing Sioux Falls but hitting EROS head-on. The storm pounded EROS with 20 minutes of baseball- to softball-sized hail. Landsat 5 passed overhead three days later and documented the aftermath.

Healthy crops normally surround Sioux Falls. The healthy crops appear bright red because red represents the near-infrared light (that human eyes can’t see) that is highly reflected by healthy vegetation. Most of the crops grown in this area are soybeans and corn. Some of those fields turned gray in the 1997 image, where the hailstorm converted the cropland into bare soil. The conversion was temporary, however, as the Landsat 5 image from 1998 demonstrates. The cropland is back to the expected red, indicating healthy crops.

The British Antarctic Survey has studied Brunt Ice Shelf in person since 1955. Scientists at their Halley Research Station study Earth, atmospheric, and space weather processes. Since 2012, the station has been made up of eight interlinked pods, built on skis so they can be moved, such as during the Antarctic summer of 2016–2017. Referred to as Halley VI Research Station, it was moved to the eastern side of Chasm 1.

The station is constantly on the move anyway, since the floating ice shelf flows at a rate of up to 2 km per year toward the west.

Images from Europe’s Copernicus Sentinel-2 satellites show the station’s previous location in 2016 and new location after that. Even at this satellite’s 10-m resolution in natural color images, the station consists of only a few pixels.

Another rift appeared on the Brunt Ice Shelf in October 2016 and quickly extended eastward. Dubbed Halloween Crack, it’s located about 12 km north of Halley Research Station. By March 2017, the crack cut 35 km across the ice shelf. By October 2018, it was 60 km long.

These images from Landsat 8 use only its panchromatic band. The resolution of this band is 15 m, rather than the 30 m of the other bands. It makes the images grayscale, which in Antarctica is not much different from natural color.

Do you see Halley Research Station move into view in the lower right of the images?

How about another rift forming in the last images and an iceberg breaking from the shelf? More on that in the “North Rift” sections.

Sydney Harbour defines the city and makes it recognizable worldwide. Parks, reserves, and gardens line the 240 kilometers of shoreline of this beautiful natural harbour. Any green that you see in the images along the harbour are parks or reserves—along with a few golf courses.

The Sydney Harbour Bridge crosses the harbour. This well-known Australia landmark opened in 1932. The height of the top of the arch is 134 meters above sea level. The 1-kilometer-long bridge is visible in the Landsat images, but you have to look closely.

Located near the bridge is one of the world’s most recognizable buildings and part of Sydney Harbour’s landscape. The Sydney Opera House was completed in 1973. It is seen as a few bright pixels in the images, on the end of the point nearest the bridge.

The 2000 Summer Olympic Games took place in Sydney. Can you spot the location of Sydney’s Olympic Park?

Another consequence of the dam is the burial and inundation of the Hasankeyf archaeological site. The site has evidence of human habitation dating back 12,000 years.

Before the reservoir inundated the town, residents were relocated to high ground north of the river. Named New Hasankeyf, the new town is home to a few historical structures moved from their original locations, including a tomb, a mosque, and an ancient bath. While a section of the old town remains above the water, many archaeological sites were submerged beginning in 2019.

The declassified Hexagon satellite image also shows enough detail to reveal Hasankeyf’s previous location.

The Biloxi-Chitimacha-Choctaw community began in the early 1800s when Frenchman Jean Marie Naquin married Pauline Verdin, a Native American. Naquin’s family disowned him for this, and the couple moved to the delta region, where his father had traveled many times. Despite being disowned, Naquin named the island where the couple settled after his father Jean Charles Naquin.

Naquin and Verdin, along with the other original inhabitants of the island, had also moved there to escape the Trail of Tears, the forced removal of Native Americans from the southeast in the 1830s to present-day Oklahoma. They sought refuge in the dense forested swamps of the Mississippi Delta, which white settlers thought were uninhabitable.

Most of Jean Marie and Pauline’s children married descendants of the Biloxi-Chitimacha and Choctaw tribes. Other families moved to the island after intermarriage between the families. By 1910, the island population had grown to 16 families, all descendants of the first families to settle there. They lived by fishing, gathering oysters, trapping, and hunting.

By the 1950s, there were around 80 families living in Isle de Jean Charles, and the island spanned 33,000 acres. Today, the island has shrunk to 320 acres and fewer than 30 families remain. Many residents moved elsewhere, fracturing the community. With the people scattered, the heritage and traditions are fading away. Afraid of losing their culture, the community is now planning another resettlement, possibly the only way for them to adapt to the changing Louisiana coast.

The tribe has been planning resettlement since 2000, and in January 2016, the U.S. Department of Housing and Urban Development (HUD) awarded the tribe $48 million to help them move. A possible location has been chosen that would allow the community to regain their culture with traditional hunting, fishing, and agriculture. The site is a 515-acre sugar farm north of Houma. Resettlement, however, is a difficult concept to accept. Tribe members say losing the island is like losing a family member.

Moderate resolution imagery from Landsat (30 meters) and Sentinel (10 meters) shows a broad view of the changes around the island over time. Landsat’s history goes back to 1972, with 60-meter resolution imagery to show a long view of the change.

Sentinel-2A

Imagery from the Europe's Copernicus Sentinel-2 satellite is distributed by the USGS through EarthExplorer.

Landsat data can track the spread of the outbreak and monitor defoliation. Comparing newly acquired Landsat observations with long-term average conditions modeled from Landsat time series makes it possible to detect changes in vegetation “greenness” in near-real time.

These forest condition assessment maps represent changes in expected forest reflectance signatures compared to average patterns over an 11-year baseline. Blue pixels indicate forest conditions that are within the normal range of variability, while yellow, orange, and red show sustained decreases in vegetation greenness that coincide with caterpillar stages of the spongy moth life cycle and are indicative of varying degrees of defoliation.

Black is non-forest, according to National Land Cover Database 2011 (NLCD 2011) classifications.

Data from Landsat not only detects initial outbreak and magnitude of the defoliation but also recovery later in the season.

The Huang He River in China is a wanderer. Its lower reaches have changed course many times, moving the delta up and down the coast several hundred kilometers over the centuries.

The Huang He (Yellow) River is over 4,800 kilometers long. It’s the 2nd longest river in China and the 5th longest in the world. It’s also the muddiest river on Earth. On its long journey, the river crosses a soft plateau that’s covered with fine, wind-blown soil. The river carries away millions of tons of this delta-building material every year. The Huang He derives its yellow color from fine particles of mica, quartz, and feldspar.

The river shows up well in most of these Landsat images because of the high sediment load, which reflects light. The sediment even shows up in the water of many of these images where the river flows into the sea.

Unlike many glaciers in Alaska and around the world, Hubbard Glacier is thickening and advancing. Hubbard Glacier has a large accumulation area, like a river with a large watershed. This large area of snow in the mountains upstream either melts or flows down to the end of the glacier, and Hubbard steadily grows. In fact, Hubbard Glacier has advanced 1.5 miles, or about 2.4 kilometers, since 1895.

These Landsat images illustrate an unusual event that was observed twice at the terminus of Hubbard Glacier. Hubbard temporarily blocked Russell Fjord (a long, narrow inlet of the sea) from the rest of Disenchantment Bay and the Gulf of Alaska. It’s even possible that the glacier could one day permanently block the fjord.

Hurricane Katrina was one of the most intense and costliest hurricanes to hit the United States. On August 28, 2005, Katrina was a category 5 storm (on the Saffir-Simpson scale) in the middle of the Gulf of Mexico. It made landfall the next morning as a strong category 3 storm with sustained winds of 125 miles (200 kilometers) per hour.

Flooding in New Orleans began early that morning, and water continued pouring into the city until September 1. State health departments estimate that Hurricane Katrina caused about 2,000 deaths, most occurring in Louisiana. About 75 percent of the New Orleans metropolitan area was flooded. The storm caused an estimated $80 billion in damage.

Landsat recorded the devastation and continues to monitor the region’s wetlands. New Orleans, Louisiana, is near the bottom of the images along the Mississippi River. The city lies just south of Lake Pontchartrain. Hundreds of square miles of wetlands were lost after Katrina. Some marshlands became permanent water bodies. Some projects now aim to bring back marshlands because of their value in defending the coastline from storms.

(Black stripes run through the Sep. 15, 2005, images because of the Scan Line Corrector failure on Landsat 7 in May 2003.)

The Sentinel-2 satellites from the European Space Agency (ESA) use infrared imaging to highlight certain information about the land surface. In the near-infrared wavelength of light, actively growing vegetation appears red in these images that show the lake more closely at a resolution of 10 m.

The cropland appears in bright red around the lake, and the greenhouses are the light blocky shapes. However, bright red swirls also appear on the surface of the lake, and the extent and location change in each image. Sentinel’s near-infrared proves that it’s vegetation and that it’s alive.

The nuisance plant is water hyacinth, a fast-spreading, free-floating plant that forms moving, impenetrable mats. It hinders boating and fishing and interferes with the ecology of the lake.

European settlement in the early 1900s likely brought hyacinth to Lake Naivasha. Around 1920, hyacinth was tossed into the lake to beautify it. Low nutrients restricted it to the shallow northern shores for decades. It spread to other parts of the lake in the 1980s. The flower farms increased at this time, using so much water that the lake level dropped, exposing hyacinth seeds. As the lake became over-enriched with farm runoff, the hyacinth thrived.

In the Landsat images in the other sections, the near-infrared wavelength is used to make vegetation appear green. The extent and location of the hyacinth on the lake’s surface changes over the years in those images, visible as the bright green shapes on the lake.

The hyacinth was at first limited to protected bays and estuaries. The western part of the lake has been most affected recently, but these images do show it spreading over various parts of the lake. Scientists will continue to use Sentinel, Landsat, and other remote sensing instruments to track the changes caused by the blooming cut flower industry.

The effects on the hydrology in the region where mountaintop mining takes place is not well understood—how does this mining activity affect the movement and storage of water?

The EPA, in a 2011 report, explains that stream ecosystems are affected by mountaintop mining in five principal ways:

• Springs are permanently lost when buried under valley fill.
• Elevated levels of chemicals are found downstream.
• Degraded water quality in streams can be lethal to organisms.
• Selenium levels are elevated in the water, toxic to fish and birds.
• Fish communities are degraded.

One way hydrology changes is through the reclamation process. Heavy equipment compacts the soil, which inhibits water infiltration and natural succession. That is, the compacted soil doesn’t soak in water the same way as it did before when it was natural forest. Native trees do not grow well in this compacted soil, where rainfall runs off faster. Even when grasses are planted immediately during reclamation, runoff is increased in these areas.

Increased runoff can lead to more frequent downstream flooding. Some fill areas that have large volumes of crushed rock can actually increase watershed storage. But how and to what extent these areas control runoff are not clear.

Furthermore, groundwater samples from mined areas after reclamation have been found to contain more mine-derived chemicals than water from unmined areas. These chemicals (lead, aluminum, chromium, manganese, and selenium) would otherwise remain sealed up in the coal and rock. Water flowing through the valley fills picks up these chemicals and flows into the streams. Researchers have linked declines in stream biodiversity to an increase in these contaminants, affecting the freshwater species found there.

An aerial image from 1952 shows Lake Thompson as a wetland, with about one-third of it as open water. Landsat began observing the area in 1972 with multispectral imaging that includes visible and near-infrared bands, which are great at distinguishing open water from dry land.

Water levels have fallen somewhat since the 1990s but continue to fluctuate depending on annual precipitation. Some shoreline and shallow areas change between dry land, marshland, and open water.

Most lakes in the PPR are closed systems. That means they do not have an outlet for water to flow out. It also means they can change a lot based on variable rainfall and snowmelt from year to year. As these water bodies expand, they can connect to other water bodies that were previously disconnected.

From around the 1890s until the mid-1980s, most lakes around Lake Thompson were closed lakes, disconnected from one another. Above average precipitation in 1984 brought an increase in tributary inflow into the lakes of Kingsbury County. Above average rain continued for two more years, and a chain reaction began that went something like this: In April 1986, Spirit Lake overflowed and drained into Mud Lake. Mud Lake then overflowed, its water draining to Silver Lake by way of a drainage channel. Silver Lake then overflowed into Lake Thompson.

But that’s not all.

Lake Preston also overflowed around that time and drained into Lake Whitewood, which subsequently rose above its outlet and drained into Lake Thompson. By October 1986, Lake Thompson ceased to be a closed basin when it drained into the East Fork Vermillion River. Water from the East Fork Vermillion River subsequently flows into the Missouri River. This marked the first time Lake Thompson had overflowed in over 100 years.

The Mille Lacs Lake ice roads are short-lived. Ice houses need to be off the lake before the ice breaks up in the spring. The deadline varies by year, depending on ice conditions. It’s usually in late February to early March.

The number of ice houses on Mille Lacs Lake can exceed 5,500. Ice fishers are after walleye, northern pike, muskie, yellow perch, largemouth and smallmouth bass, and tullibee.

It’s possible for the roads to be obscured after a snowfall, to the extent that they need to be plowed. So some images show the roads as less clear.

The world’s longest ice road connects Yellowknife to three diamond mines: Ekati, Diavik, and Snap Lake. Of the 475 kilometers (300 miles) of ice road, 86 percent of it is across frozen lakes.

The ice road is the only overland supply route for the mines. Each winter, a year’s worth of fuel, construction material, heavy mining equipment, and explosives are trucked to the mines. The road provides the most cost-effective method for transporting these supplies.

Open only 8–10 weeks of the year, the ice road is open from mid-January to March. It has to be rebuilt each year. Work on the road starts soon after Christmas. When the ice is 1 meter (42 inches) thick, it can support a truck fully loaded with over 40 metric tons (44 tons) of fuel.

Full trucks traveling north have a strict speed limit of 25 kilometers (15.5 miles) per hour. Empty trucks heading south can use the express lane and go up to 70 kilometers (43.5 miles) per hour. The number of trucks the road handles per year varies. Just over 6,000 truckloads were driven north during the 2013 season.

This place is so far north it’s too dark for satellite imaging in the middle of winter. Early summer, late summer, and late winter images are shown for comparison. There is still some ice on the lake in the July images. In the April images, the straight dark lines across the ice are the temporary roads.

Major rifts have formed near a distinctive feature called the McDonald Ice Rumples. The feature, rising about 10 m above the surrounding ice shelf, may be responsible for the relative stability of Brunt Ice Shelf over most of the 20th Century.

Ice rumples form when ice flows over a rocky formation on the seabed. As the shelf moves toward the ocean, ice collects behind the rock and wrinkles. This rocky formation impedes the flow of ice, causing pressure waves, crevasses, and rifts to form at the surface.

Through this Landsat time series, the feature that causes the rumples remains stationary, while the ice shelf and its rifts flow west.

Within this scene is one of the largest waterfalls in the world. On the border between Brazil and Argentina on the Iguazú River, 275 falls collectively make up Iguazú Falls. “Devil’s Throat” is the tallest at 80 meters.

Landsat’s 30-meter resolution doesn’t reveal the falls in great detail. But in the 2011 image, a blue-white line at the location of the falls points down toward the southeast. This line is the foamy water crashing over the Devil’s Throat portion of the falls.

A runway is visible southwest of the falls. This is Cataratas Airport, which serves the city of Puerto Iguazú, Argentina, and provides access for tourists to visit the falls.

Iguazú Falls was named one of the New 7 Wonders of Nature in 2011.

Iguazú National Park is located in Argentina on the border with Brazil and Paraguay. Its boundary is sharply defined as the bright green section on the right of the images. The Brazilian side of the park, north of the Iguazú River, is called Iguaçú National Park.

The park is almost an island of southwestern Atlantic rain forest, one of the few remaining original areas of this type of tropical rain forest. The Atlantic rain forest is distinct from the Amazon and once stretched along most of Brazil’s Atlantic Coast and inland several hundred kilometers. In 1973, there were some cleared areas just north of the Iguazú River in Brazil, but they have since regrown.

These images clearly demonstrate the effect of differing land use policies surrounding the park. Paraguay lies west of the Paraná River, which runs vertically through the center of these scenes. Paraguay has permitted complete development of the land. In 1973, the area seen in these images was vegetated, but by 2011, nearly all the land on the Paraguay side appears to be under human development, with a patchwork of cleared and agricultural areas.

The deforestation in Paraguay begins with the telltale fishbone pattern. Roads built into the forest are the entryway into clearing the land for agriculture. On the Argentina side of the river, development is considerably more modest than in Paraguay. The bottom middle part of these images shows a different forest management practice. The oddly shaped patterns of deep green are forest plantations used for lumber and pulp. While intense transition from forest to agriculture can harm the land and environment, these plantations can reduce soil erosion, improve water quality, increase carbon sequestration, and provide habitat for many species.

On the border between Brazil, Paraguay, and Argentina are some curious land use features. Paraguay lies west of the Paraná River, which runs north to south down the middle of the images. The Iguazú River flows toward the west and into the Paraná River. North of the Iguazú River is Brazil, and Argentina is to its south.

At this location, we can see the effects of deforestation of the rain forest, one of the largest dams in the world, a spectacular set of waterfalls, and a sharp contrast between protected land and intense development.

For centuries, people living in what is now the Netherlands have used various strategies to control the water levels in this low-lying country. The alteration of this landscape continues as residents work to improve farmland and protect inhabited areas from flooding.

Beginning in 1932, Dutch engineers created a series of dikes to drain water from an inlet of the North Sea. The reclaimed land increased the land area of the Netherlands that could be used for agriculture.

These images illustrate the progress of the Netherlands' diking and draining of the IJsselmeer region. The IJsselmeer is a lake on the coast of the Netherlands. (This lake, or meer, is named after the IJssel River and is pronounced EYE-ssel-mare.) In the satellite images, water appears blue-black, and vegetation appears red. Highly reflective areas like pavement or bare soil appear light blue or blue-green. Amsterdam can be seen in the lower left of the images.

Until 1932, this area was the Zuiderzee (pronounced ZIGH-dr-zee and meaning Southern Sea), simply a saltwater inlet of the North Sea. By 1968, the Dutch had transformed 1,979 km² of the Zuiderzee into blocks of usable land, called polders. Here is how that typically happened:

• In 1932, the Dutch completed a dike across the mouth of the Zuiderzee, creating the IJsselmeer. This dike can be seen in the upper middle portion of these main images. The freshwater from the IJssel River flushed out the saltwater, creating a lake.
• Between 1930 and 1968, dikes were built around five portions of the IJsselmeer.
• The polders were drained using pumps.
• Reeds naturally grew on the former sea bottom. To help dry out the soil, the Dutch let the reeds grow. Transpiration moves water into the air faster than evaporation alone would.
• When the soil dried, the reeds were cleared and colza was planted. Colza is related to cabbage and turnips.
• The colza was cleared, and grain crops were planted.
• The polders were cultivated for up to five years before the land was ready to produce commercially.
• Land was then leased to commercial farmers, or towns were built.

The first of the five polders (Wieringermeer, in the northwest) was actually diked directly from the sea, not from the IJsselmeer. It was dry two years before the mouth of the Zuiderzee was closed off.

The Ilisu Dam is 440 feet high and a mile wide. Generating 1,200 megawatts of electricity, it’s Turkey’s fourth largest dam in terms of power generation.

The decline in water flow for the Tigris River can lower the water quality downstream, especially during a drought. Where the Tigris drains into the Persian Gulf in southern Iraq, the lower flow can cause saltwater intrusion from the Gulf. This hinders the recovery of the Mesopotamian Marshes.

Declassified satellite imagery reveals a now-inundated village, Koctepe, just above the location of the Ilisu Dam. The Hexagon satellite image has a resolution of 2–4 feet, enough detail to see the small village by the Tigris River.

The Tigris and Euphrates Rivers flow into the historical cradle of civilization. Dams built on these rivers in recent decades have altered the landscape with large reservoirs easily seen in Landsat imagery.

Turkey has built 22 dams as part of its Southeastern Anatolia Project, as the country works toward energy independence. The country’s last major dam planned for the Tigris is also its largest. A reservoir began filling behind the Ilisu Dam in July 2019.

Over its five decades, the Landsat program has provided a record of both natural and human-caused landscape change.

These three Landsat 5 images show several rivers in southern Illinois and Indiana, USA, during normal and flooded conditions. Peak flooding was observed in this area on June 10 and 11, 2008. The clear Landsat scene from June 11, 2008, and the clear image of “normal” conditions from June 9, 2007, allow us to compare the scenes and see exactly what damage a flood of this magnitude can cause.

Rainfall amounts ranging from about 2 inches to more than 10 inches fell in this area on June 6–7, 2008. Spring was wetter than normal, so the heavy rain easily saturated the ground. The rivers quickly rose to exceed flood stage.

Satellite images can help authorities respond to disasters such as floods. The images can help local authorities see the amount of flooding and where there is damage to property. The extent of the flood can be mapped so that response teams can view where they are needed and respond quickly.

These images show the Imperial Valley, on the border of California and Mexico. The international border is plain in the images because of the different intensity of vegetation, shown in bright green. These images also show the Salton Sea and the growing cities of El Centro, Calexico, and Mexicali.

This valley, also known as the Salton Sink, the Salton Basin, and the Salton Trough, is actually an extension of the Gulf of California, cut off from the Gulf by the Colorado River’s delta fan. The valley was renamed Imperial by turn-of-the-century land investors. The area south of the U.S.-Mexico border is known as the Mexicali Valley.

At the bottom of the sink lies the Salton Sea, the largest lake in California. It lacks an outlet to the ocean and lies 70 m below sea level. About 85% of the sea’s inflows come from agricultural runoff, and its waters are 37% saltier than the Pacific Ocean.

The sea’s water level had been kept steady by runoff from irrigation canals. But water levels have been decreasing since around 2005 as less runoff has been entering the sea. As the water evaporates, the sea shrinks.

NLCD images of western Las Vegas show the urban expansion that took place. The land cover classes that expand noticeably in these images are the developed classes. With these classes, NLCD can be used to track changes to impervious surface.

Impervious surfaces include roads, buildings, and parking lots—surfaces that do not allow rainwater to soak into the ground. The extent and density of impervious surface can affect water quality and flooding severity in urban areas.

In a forested area, for example, most rainfall soaks into the soils and is stored as groundwater, slowing the discharge into streams. Flooding in these areas is less significant. In urban areas, however, much more water runs off into streams quickly and increases the likelihood of severe flooding.

Studying impervious surface change allows scientists to quantify the extent of developed land cover regionally and nationally. NLCD is widely used to evaluate effects on hydrological and ecological systems in many urban areas.

Impervious surfaces are best measured with satellites. They cannot be easily or cost-effectively measured on the ground.

The impervious surface product provides a value for every land cover pixel mapped as developed. The product provides a 0–100% value for each pixel. Black is no impervious surface.

Scientists studying the effects of urban growth are concerned with surface imperviousness—the amount of land covered by human-made features such as asphalt, concrete, and rooftops. These surfaces are impervious to rainwater. On these surfaces, rainfall does not soak into the land; instead, it runs down the streets or across parking lots, often pooling up in low-lying areas, increasing the risk of local flooding.

During heavy rainfall, areas of increased impervious surface can be more vulnerable to flash floods. The excess water flows directly to streams, often by way of storm water drains. This directly increases streamflow and reduces the amount of water that infiltrates into the ground.

In these images, Pune itself is at the bottom right at the sharp bend of the Mula-Mutha River. Toward the top center of these images is Pimpri-Chinchwad. The pink, maroon, and lavender tones are the colors associated with impervious surfaces. In many areas, urban areas are expanding over what was once either agriculture or bare ground, visibly increasing impervious surface.

Even at Landsat’s 30-m resolution, roads and structures can be seen to increase across the landscape. Some individual buildings can be seen, too—the bright rectangles to the north. Green rectangles are farm fields in the center of the images. Over time, many of them convert to built-up impervious surface.

Scientists use hydrological models to quantify how streamflow changes in areas of increased urban growth. They can better understand how the entire watershed is changing due to urbanization. In the Mula-Mutha subwatershed where Pune is, average streamflow increased from 179.14 m³/s to 185.23 m³/s between 1980 and 2009.

Landsat data can be used to map impervious surfaces and quantify the effect of the increased runoff it causes. Landsat can also be used with the European Space Agency’s Sentinel-2 satellites to get more frequent coverage of study areas.

A large oil reserve sits under the boreal forest of northwestern Alberta, Canada. Open pits are created to reach the oil that lies less than 75 meters (246 feet) from the surface. To extract oil that is too deep for surface mining operations, in situ mining, or “in place” mining, is used. Mining companies use steam and gravity to bring the sticky oil to the surface. Landsat reveals where this method is taking place.

Two parallel L-shaped wells reach into the deep oil sand deposit. One injects steam through holes in the pipe. This warms the oil and lowers its viscosity. The oil then flows down to the well below where it’s pumped to the surface.

This method is not as visible in the Landsat images as the surface mining is. Each well needs a “well pad,” a small area of boreal forest cleared. A growing number of small dots appear in a grid pattern over the time series images. A vertical line appears near the top of the 2009 image. This airport was built to fly in workers close to the mining sites.

The PRD was mostly rural before the 1978 reforms began. The major industries were farming and aquaculture. The major crops were rice, sugar cane, peanuts, soybeans, bananas, and oranges. Fish were raised in a huge system of artificial ponds.

The region’s economic growth is now outpacing the rest of the country. The relatively small farming and fishing villages have become large metropolitan areas. The PRD is a major center for telecommunications, biomedicine, robotics, genomics, and manufacturing of electronics, household appliances, computer equipment, toys, garments, footwear, plastic products, and ceramics.

The dark green areas in between cities seen in these images are the region’s dike-pond system. These artificial wetlands have been there since the Tang Dynasty, over a thousand years ago. Grass carp are grown for food in the ponds. Vegetables, sugar cane, and other plants are grown on the dikes. Mulberry trees are also grown on the dikes, and the leaves are used to feed silkworms.

In this area south of Foshan, the dike-ponds are diminishing. The vast increase in manufacturing puts pollutants into the delta, reducing the amount of fish produced. Additionally, infrastructure is built on land that once had fertile soils and fish ponds. However, the dike-ponds are also extending toward the south and east, replacing farmland. Their extent now covers a wider range and is increasingly fragmented.

The Dead Sea has no outlet. The only way water exits the sea is by evaporation. When the water evaporates, it leaves behind dissolved minerals, making the water even saltier.

Those minerals produce the basis for a valuable potash industry. Companies from both Israel and Jordan extract this raw material for fertilizer from the evaporation ponds in the southern basin. The industries that produce the potash pump water from the Dead Sea into these evaporation ponds. Potash is gathered by moving water from one evaporation pond to another.

Current studies suggest that as Dead Sea water use continues, sea levels could decline to 100 meters below the 1960s level by 2050. It would then become too expensive to pump water into the evaporation ponds.

Other uses of Dead Sea salt include

• skin products
• cosmetics
• bath salts
• water conditioning
• road de-icing

Normally, political boundaries are not visible from space. But in this series of Landsat images, we do see a political feature. The curved line in the southern basin is the border between Israel to the west and Jordan to the east.

In natural color satellite images of wildfires, smoke often obscures the view of the ground. Landsat uses several infrared wavelengths, or bands, of light. If some of those infrared wavelengths are used, then different details about the location of burned areas emerge.

The combination of bands we have been looking at use two infrared wavelengths along with one visible band (green). This combination shows freshly burned areas as deep red and vegetation as green. Smoke from fire appears blue. The infrared bands help us see the burned areas clearly, but the smoke can still get in the way.

The third image at the left uses Landsat’s thermal infrared band and a shortwave infrared band to cut through the smoke to see ground conditions. In this false color image, burned areas are red-orange. This view can help people see where fire might be approaching populated areas.

On the edge of the Sahara Desert lies one of the world’s most productive wetlands. The Inland Delta of the Niger River in Mali is a vast expanse of lakes, channels, and marshes. The Niger River divides into countless channels and forms the largest wetland in Western Africa. The river and wetland form an important water resource for Mali, a landlocked and generally dry country.

This delta floods seasonally from September to December, as rainfall from the river’s headwaters in the Guinea Highlands reaches the delta’s vast flat floodplain. The southern part of the delta is low-lying floodplain with expanses of wetland grasses and reeds. The northern part has sand ridges that emerge from the water during the flood season. The seasonal flooding supports fisheries, pasture, and rice farming. Over 1 million people depend on resources in the delta.

A more up-close look in the Landsat images helps you to see the progression of clearcutting and regrowth. The colors in most of these images are a patchwork of tan, white, and various shades of green. First, notice that the landscape changes a lot during this time. How can you ensure that this series of close-up images is the same exact area? Identify features that do not change throughout the series, such as a river, as you click through the time series.

Next, notice the difference between the shades of light green and dark green. How would these two areas look if you were standing on the ground? Dark green indicates taller trees and an older forest. Light green areas are only beginning to recover from past logging, so the young trees in these areas are not very tall yet.

The tan areas are fresh clearcuts. Using the infrared wavelengths of light that Landsat can detect helps to more clearly see those cleared areas. Compare the amount of tan seen in these images throughout the time series. Can you tell how long it takes for these cleared areas to look as they did before the clearing took place?

Remote sensing means observing something from a distance. Satellites observe the Earth from space and help scientists study large tracts of land and how that land changes over time.

The sensors onboard the Landsat satellites use reflected light to detect electromagnetic energy on the Earth’s surface. The level of energy is represented by the electromagnetic spectrum, which is the range of energy that comes from the Sun. The light from the Sun that we can see is only a small part of the electromagnetic spectrum and includes the colors of the rainbow. Satellite sensors record this information in different portions of the electromagnetic spectrum, which is measured in wavelengths. Landsat satellite sensors detect both visible and infrared light.

When satellite images are made, these “invisible” types of light are assigned visible colors to represent them so that our eyes can see the data.

The economic viability of this huge project has been unclear. It’s impossible to say exactly how much the Toshka Project has cost so far—estimates of the project’s final cost range up to $70 billion USD.

If more water were to be pumped from Lake Nasser to irrigate hundereds of thousands of hectares of farmland outside the Nile basin, the lake may spill into the Toshka lakes only when there is flooding rains upstream. That's what happened in late 2019. The animation below uses images from Landsat 8 and Sentinel-2 to show the eastern lake filling to capacity—and more—starting in early October.

Will people find enough incentive to move to the area and develop it into a “New Nile Valley”? Landsat will continue to track the status of the Toshka region and its agricultural development.

There has been irrigation along the Senegal River in the Richard Toll, Senegal, area since the 1940s. With little dissolved salt, the quality of water in the Senegal River is generally good for irrigation. However, proper drainage and cropping schedules are needed to keep levels of alkaline content from accumulating in the root zone.

In the images, the many bright red fields are mostly sugarcane and rice, and virtually all of them are irrigated. The amount of irrigated land increased greatly in this time frame, and new irrigation canals are visible. The irrigated crops are able to grow in the dry season because they are not dependent on rainfall.

On the Mauritania side of the river, growth in agriculture is limited by poor soil quality and lack of agricultural education. Most of the country's food is imported. Since almost half of Mauritania's population lives at or below the national poverty level, the imported food is not always affordable. In 2007, the people's distress was expressed by food riots.

In the 2011–2012 growing season, the Mauritanian government began some new strategies to increase the yield and amount of crops grown. By training young farmers about agriculture, investing money into more irrigation, and introducing genetically modified crops that can survive in Mauritanian conditions, leaders of the country are hopeful that better times are to come for farming.

This series of images of southwestern Japan shows how one change can have far-reaching consequences.

The Ariake Sea is an important fishery and resource for cultured nori (seaweed). The controversial Isahaya Bay Reclamation Project has been blamed for recent reduced harvests of fish and nori in the sea. A dike across Isahaya Bay, which was built to create more farmland, has reduced the tidal current mixing of the sea. These weaker tidal currents have led to abrupt changes in the marine environment.

The 7-kilometer sea wall (dike) was completed in April 1997, cutting off Isahaya Bay from the waters of the Ariake Sea. It separated thousands of hectares of tidal flats from the Ariake Sea and turned what was once Japan’s largest area of tidal lands into 1,500 hectares of farmland.

In the Landsat series of images, the Ariake Sea is the large body of water, and Isahaya Bay lies to its west. The dike can be seen as the straight line in the 2003 and later images, separating dark blue from light blue colored water. Black or very dark blue indicates deep water, and light blue represents shallow water. Forested areas are green, and urban areas are pink. Cropland is distinguished by its rectangular pattern: green shapes are fields with crops, and pink shapes are fields with no crops growing at the time of the image.

The name Aral means Island. The sea did once have many islands. However, many of them stopped beings islands as the sea dried up. Two of the prominent islands were Vozrozhdeniya and Barsa-Kelmes. Throughout the series of images, they first become larger, then they become peninsulas. They are now fully connected with the mainland.

Vozrozhdeniya Island became infamous as the location of the Soviet Union’s secret biological weapons program. In the 1950s, Vozrozhdeniya was a small, isolated island in the middle of the sea. Until the collapse of the Soviet Union in 1991, various pathogens were tested, modified, and possibly weaponized on this island.

Vozrozhdeniya Island grew in size and joined the mainland around 2001. As the remote site became accessible, there was concern that the pathogens might have survived and spread to the mainland. In the early 2000s, experts from the United States helped Uzbekistan decontaminate the former island.

The former island Barsa-Kelmes is a nature reserve, established in 1939. Its natural isolation gave it great protection. But in 1999, the island became accessible, possibly threatening its pristine nature. It is now a desolate plateau, more vegetated than the surrounding dried sea bottom. However, this vegetation degraded as the sea disappeared.

For more information, see the book by Micklin and others, listed in the References section, pages 4 and 22.

Is Louisiana falling into the sea, or is the sea inundating Louisiana? It’s actually a bit of both. And to the inhabitants of a tiny island on the bayou, an island getting tinier by the day, it hardly matters. They just know their home is gradually becoming uninhabitable.

A USGS report estimates that Louisiana, which experiences more coastal wetland loss than all other states in the conterminous United States combined, lost 5,197 square kilometers (2,006 square miles) of land from 1932 to 2016. Places are actually being removed from maps—NOAA is deleting labels from its maps for bays, islands, streams, and other features that are now underwater.

A combination of factors is causing this coastal land loss. Marshland, which historically served as protection against storms, has been carved up for oil and gas production activities. The marshland is then open to saltwater intrusion. The low elevation of the region makes it especially vulnerable to sea level rise.

These factors have an immediate effect on the Biloxi-Chitimacha-Choctaw community on Isle de Jean Charles, about 75 miles south of New Orleans. The island has lost 98% of its landmass since the 1950s. Once 5 miles wide and filled with lush cypress groves and cow pastures, barely a half square mile of the island remains above water.

The saltwater intrusion and loss of land have made it impossible for residents to continue the tradition of growing their own produce. They can no longer grow their own herbs for medicine. The increased cost of living from having to shop for food they once provided for themselves is a struggle.

A variety of images from the EROS archive shows how the island, and the surrounding delta, has changed. A combination of different types of imagery is needed in this location to accurately track the changes over time. High resolution is needed to see the small island, but a frequent repeat cycle reveals the larger changes taking place across the delta.

The southern tip of Spitsbergen is called Sørkapp Land. Hornsund Fjord nearly divides Spitsbergen and Sørkapp Land into separate islands. Only an isthmus of ice separates the two. The narrowing isthmus could someday make Sørkapp Land a new island.

In fact, new islands have formed in other locations on the Arctic coasts of Europe and Greenland. In places where the bedrock is below sea level, sea water inundates the space left by retreating glaciers.

The isthmus between Spitsbergen and Sørkapp Land is rapidly thinning and recessing. In 1899–1900, the isthmus was 28 kilometers wide. According to one source, the isthmus was 6.2 kilometers wide as of 2013. Based on the 2019 Landsat image, and measuring the width of the isthmus using geospatial software, the isthmus has narrowed further to about 5 kilometers wide. This ice is grounded well below sea level, so when the ice melts, there will be a strait of open water between the two lands.

The same source estimates that the glaciers on the isthmus will retreat enough to make Sørkapp Land an island by 2030–2035. The isthmus decreased from 12.3 kilometers in 1990 to 6.2 kilometers in 2013, with a rate of decrease of about 270 meters per year. This annual decrease is close to matching that 5-kilometer measurement for 2019; in fact, the decrease is slightly faster than the source’s estimate.

With the launch of Landsat 9 expected in 2021, Landsat satellites will continue monitoring the progress of these glaciers to see whether Sørkapp Land does indeed become a new island in the Svalbard archipelago.

The world’s largest hydroelectric power plant is on the Paraná River between Paraguay and Brazil. The Itaipú Dam is capable of producing 14,000 megawatts of power. The reservoir behind the dam formed in 1982 and covers 1,350 square kilometers.

The entire dam is nearly 8 kilometers long. The maximum discharge capacity of the spillway is 62,200 cubic meters per second, 40 times the mean discharge of Iguazú Falls.

Just below the dam is the rapidly expanding city of Ciudad del Este. Its estimated population in 2015 was 317,525.

Joe Pool Lake, southwest of Dallas, is not present in the 1974 image and shows up in the 1989 image. Impoundment of the lake began in 1986 and opened for fishing and recreation in 1989.

Because of the global trend in retreating glaciers since the start of the 20th century, proglacial lake formation has increased. Proglacial lakes are water bodies at the edge of a glacier and form during glacial retreat. Jökulsárlón Lake is an example of this process.

Also called Jökulsárlón Lagoon, this tidal inlet was excavated during the last glacial advance, which was about 26,500 years ago. Because of the glacial retreat, the lagoon is expanding at about 0.5 square kilometers per year. By 2014, the lagoon covered about 25.4 square kilometers (9.8 square miles), about the size of Block Island, off the coast of Rhode Island.

Jökulsárlón Lagoon connects to the Atlantic Ocean by way of a 100-meter wide and 20-meter deep engineered channel. Because it is connected to the ocean, tides affect the lagoon level. Water flows in at high tides. Its daily tidal range is about 2–3 meters. During summer, meltwater from the glacier increases, bringing freshwater into the lagoon, but this freshwater does not entirely flush the seawater out.

The bright specs in the Landsat images are icebergs in the lagoon that broke off the end of the glacier. Sailing among these icebergs is one of the most popular tourist attractions in Iceland.

Because 10 percent of Earth’s land surface is covered by glaciers, monitoring changes to glaciers and proglacial lakes is important to predicting the impacts of glacial thinning and retreating. These studies help develop sustainable ways of living with anticipated changes.

The symbol of the new Singapore may be on the island’s west end, the industrial New Town of Jurong. In 1962, the government began clearing the jungle and building docks by digging into the shore and by extending new land out into the sea. In the 1973 image, you can see cleared and filled expanses still lying bare and bright. By 1990, you can see Jurong’s streets and plantings filling in as it spreads inland. There are obvious land extensions, and the harbor is now busy with ships.

Much of Jurong’s shipping has been oil; by the 1990s, only the Gulf Coast and Rotterdam refined more. By the late 1960s, several plants were operating along the shore, and by 1973 you can see several more on the small islands offshore, squeezing out their forests and little fishing villages. By 1990, the islands are filled, and the oil companies have begun extending them. By 2000, the islands are gone, replaced by one large “chemical island” called Jurong Island, with its own new causeway to the mainland. Further development of Jurong Island is evident in the 2009 image.

Altogether, the government planned to increase Singapore’s area by 25 percent between independence and “Year X.” Year X was commonly interpreted as 2030, but many developments have pushed ahead of schedule. It appears that this extraordinary nation’s future, like its newest land, is far from settled.

The Pu‘u ‘Ō‘ō eruption took a destructive turn in March 1990. Breakouts from a lava tube spread lava into the Kalapana community. Images show the entire community, known for its historic sites and black sand beaches, being completely covered with lava. Bright spots in the 1989 and 1991 images are active lava flows.

A church, store, and more than 100 homes were buried under 15–25 m of lava. The devastating event finally ended in late 1990 when a new lava tube diverted lava away from Kalapana and back into Hawai‘i Volcanoes National Park.

In a remote part of the Western Australia outback lies one of the world’s largest holes in the ground. Known as the Super Pit, the Fimiston Open Pit is part of what is known as the Golden Mile, where gold has been mined continuously since 1893. The mine sits right next to Kalgoorlie-Boulder, a city of about 33,000 located almost 600 kilometers from Perth.

The first gold rush here occurred around 1890. The easy-to-reach gold is gone, but small pieces and flakes remain. Work on the Super Pit began in 1989, and now at least 800,000 ounces of gold are dug out of the mine every year. According to the USGS Minerals Commodity Summaries (2018), Australia is the second largest gold producer in the world, after China.

Getting at the gold requires removing large amounts of ore. Hence, the gaping hole in the ground next to Kalgoorlie. Sparse vegetation surrounds Kalgoorlie and the mine.

Like much of Western Australia, the region surrounding Kalgoorlie and the Super Pit experiences hot summers and cool winters. The water bodies seen in the images south of Kalgoorlie and in the upper left are semi-dry salt lakes. On the eastern side of the Super Pit are the Fimiston Mill, where the ore is processed, waste dumps, and tailings ponds, which appear in the images as gray or white.

The Kara-Bogaz-Gol (KBG) is a large, shallow lagoon of the Caspian Sea. It normally covers about 18,000 square kilometers and is just a few meters deep. The Caspian Sea is the largest inland body of water in the world, often categorized as a large salt lake. It is salty because rivers (especially the Volga) flow into it, but none flow out. Water leaves only through evaporation, and the dissolved salts remain.

The Caspian is below sea level, and the KBG is 2–3 meters lower, so water flows from the Caspian through a narrow strait into the KBG, where it evaporates. The KBG is far saltier than the Caspian, and is one of the saltiest bodies of water in the world. Its salinity is 300–350 parts per thousand, while the Caspian’s is about 13 parts per thousand. (The ocean’s salinity averages about 35 parts per thousand.) Since the KBG’s water flows in from the Caspian, the Caspian’s fluctuations affect the KBG.

The first part of the LHWP was the Katse Dam. Construction started on the Katse Dam in 1991 on the Malibamats’o River, a tributary of the Orange (Senqu) River. The dam was completed in 1997 and is 710 meters long and 185 meters high.

The deep lake formed by the dam can hold 2 billion cubic meters of water, but the winding and narrow reservoir has a surface area of only 35.8 square kilometers. This small surface area minimizes evaporation loss. The 1995 image, before the dam was completed, hints at the depth of the valleys that were later filled.

This reservoir is the key to the electricity needs of Lesotho and the water needs of South Africa. A 45-kilometer long tunnel brings water from the Katse reservoir to the Muela hydropower station, which can generate 72 megawatts of electricity. Three turbines each generate 24 megawatts. An intake tower in the reservoir transfers water 82 kilometers from Lesotho to South Africa.

While the entire Aral Sea is shrinking dramatically, these images show that the northern portion of the sea, while clearly smaller than it was in 1964 and 1977, is not losing water at the same rate as the South Aral. The North and South Arals became separated sometime in the 1980s. The two had been joined by the Berg Strait. By the time of the 1987 image, this strait became more of a land bridge.

In the 1990s, a dam was built to prevent North Aral water from flowing into the South Aral. It was rebuilt in 2005 and named the Kok-Aral Dam. It caused the North Aral water level to be stabilized with a lower level of salinity. Consequently, commercial fishing began to rebound.

Throughout the 2000s, the North and South Arals continued to develop as separate water bodies, and the South Aral continues to experience more drastic changes than the North Aral.

In 1980, the Soviets dammed the Caspian-KBG strait. The Soviets intended that some water would remain in the KBG, enough to keep the salt industry operating. It was believed that even without inflow from the Caspian, the existing water might last up to 25 years.

But by November 1983, the KBG had entirely dried up. In the spring of 1992 after the Soviet Union broke up, President Sapamurat Niyazov of Turkmenistan took a spade to the dam to symbolically begin its demolition. After the demolition of the dam, the KBG soon filled, and its level has remained stable.

In these images, you can see the difference in color between the Caspian to the west and the KBG to the east. Pure water absorbs light from the sun, but the KBG water has suspended solids (including precipitated salt) that reflect more light. The KBG is also shallow, so the bottom is reflecting some light back through the water. Dry or shallowly covered salt beds appear white because they are highly reflective. Also notice the general absence in these images of bright red, which would represent vegetation.

In 2018, Hawaii was in the news as fresh lava covered 13.7 square miles (35.5 km²) at the eastern end of the Big Island. Of course, lava flows in Hawaii are nothing new. Satellite imagery shows evidence of many lava flows from the past, appearing like dark curtains draped across the southern coast of the island.

The lava flows on this part of the island are from Kīlauea, the youngest volcano on the Island of Hawai‘i. Almost all of Kīlauea’s surface is made up of rock that is less than 1,000 years old. It’s on the southeastern flank of Mauna Loa but has its own magma plumbing system, so it’s a separate volcano. This shield volcano is one of the world’s most active.

These images show devegetated shoreline along Hudson Bay in central Canada, eaten bare by growing numbers of snow geese. In the Landsat images, red signifies vegetation. Hudson Bay appears black in the upper-right of the images, and north of the Knife River Delta is a bright strip of land eaten bare by the geese.

These Mid-Continent snow geese live in coastal marshes along the Gulf of Mexico in winter and along Hudson Bay in summer. They spend almost all spring and fall migrating back and forth. Their traditional winter diet is marsh hay cordgrass, saltgrass, bulrush, and other marsh plants. Snow geese are not only grazers but also grubbers, digging up even the underground parts of plants with their strong bills.

In the spring, the snow geese fly north along well-defined paths through the prairies, stopping often to eat along the way. They linger on the prairies of the northern United States and southern Canada until about early May, then fly nonstop across the northern forests to coastal areas around Hudson Bay and farther north.

Once at the nesting ground, they start breeding. The northern summer is just long enough for goslings to hatch and learn to fly. Female snow geese have strong homing habits, returning to the spot where they were raised and even using their previous nest sites. Snow geese form large colonies of a few hundred to over 100,000 birds. Nearby La Perouse Bay (marked on this map) has the best-known colony in the world, studied by scientists since 1968.

Up in the tundra, summer is short and the soil is shallow and dry. Nesting snow geese seek out the lusher "oases" in this arctic "desert," narrow productive strips of a few hundred yards along the Bay and along some inland lakes. But even here food is sparse, since the geese leave just as the growing season is ending, with no time for the plants to recover before the next spring.

So even in a good summer, the females rely on stored energy in their bodies to produce and incubate their eggs. To produce a large clutch of eggs, they need to arrive at Hudson Bay fat and healthy. So traditionally, the amount of food available during winter and spring acted as one of the limits on the snow goose population.

European settlement brought good times for snow geese, as the Louisiana-Manitoba corridor became one long buffet line for them. By the mid-1900s degradation and draining of the Gulf Coast marshes pushed many snow geese inland, where they learned to feed on the stubble and seeds of wheat, corn, and especially rice fields. There were rice farmers in Texas who suddenly went from having no geese to flocks of thousands in the late 1940s. As Midwestern agriculture intensified, some birds stopped going to the coast, instead wintering as far north as Iowa.

This southern "gravy train" improved the snow geese's winter survival rates and springtime weight gain. Fatter, more numerous females then produced more goslings. The young flying south for the first time found more food along the way. Flocks inevitably grew; in 25 years the Mid-Continent population increased from about 2 million to 5 million birds. The colony at La Perouse Bay grew from 2,000 nesting pairs in 1968 to 22,500 in 1990.

The Kok-Aral Dam was completed in 2005 to control the water level of the North Aral Sea. This dam has prevented further decline of the North Aral Sea, and by 2011 it helped restore the water salinity level to the that of the 1960s (8 grams per liter).

A dam can be seen as early as the 1998 image. It’s the straight angled lines on the southernmost part of the North Aral. This earthen dike was built in 1992 and later replaced by a concrete dam in 2005. At times, water from the North Aral is allowed to flow southward into the South Aral through the dam in the Berg Strait.

Lake Chad was once the sixth largest lake in the world, but prolonged drought and increased water use have shrunk the lake dramatically. It now spans less than a tenth of the area it covered in the 1960s. Back then, the lake covered about 25,000 square kilometers, an area the size of the U.S. state of Vermont. Now it’s smaller than Rhode Island.

The fluctuations in lake water levels have stabilized in recent years, but it is still a dynamic environment. Social conflicts and insecurity in the region make it difficult to monitor water levels with ground-based measurements. Satellite imaging has therefore been crucial to monitoring the changes to the lake, especially with the infrared bands on Landsat sensors, which make it easier to distinguish water and vegetation.

These Landsat images show the overall transition of Lake Chad from open water to wetland. The desert appears tan, wetlands are green, and open water is blue.

The black and white 1963 image is from the film-based Argon reconnaissance satellite program, declassified in the 1990s.

Water from the Helmand River is used upstream for agriculture. The river turns west and flows across the border into Iran and drains into the Lake Hamoun wetlands.

Lake Gowd-e-Zareh, at the southern end of the Sistan basin, is the lowest level of the basin and only receives runoff when the river overflows, every 10 years on average. It has no outlet—water is lost only via evaporation, so it is a hypersaline lake. Temporary vegetation grows along the lake’s shore (shown as red in the 1998 and 2000 images) where the water from Lake Hamoun overspill is less salty.

The Sistan Basin lies on the Iran-Afghanistan border. Melted snow from the Hindu Kush Mountains of Afghanistan nourishes this dry basin. The Helmand River carries the snowmelt across the Margo Desert and into the Sistan Basin, where the water pools into Lake Hamoun. Sometimes anyway. Lake Hamoun is seasonal, and water is generally only present during the spring melt season.

Surrounded by hundreds of kilometers of arid plains, the Sistan Basin is in one of the driest regions of the world, so the three shallow lakes that make up Hamoun naturally expand and contract in the wet to dry seasons. These lakes and wetlands once supported great plant and animal diversity. But the combination of drought and water diversion for irrigation has caused Lake Hamoun to nearly disappear, along with the local bird and fish populations.

The narrow lake east of IJsselmeer is Lake Ketelmeer. The lake receives water from rivers that carry industrial pollutants from factories upstream. Those polluted sediments have settled to the bottom in a thick layer of contaminated sludge. To restore a normal aquatic environment, this material needs to be removed from the lakebed.

In the middle of the lake, in the 2010 image, a circular feature appears. This artificial island is called the IJsseloog, a repository for contaminated material dredged from the bottom of the lake. Once the repository is full, it will be capped and turned into a nature reserve.

Between 1986 and 1992, a lake appeared east of the city, along Las Vegas Wash, a riparian area. This is Lake Las Vegas, a privately owned lake that is part of a commercial residential resort. You can see that unlike Lake Mead, it is fringed with land that has been cleared for building. This appears as a bright halo in the 1992 Landsat image. After 1992, golf courses and residential and resort buildings were built up along the shores of the southern portion of the lake.

A general trend of above average precipitation in the region has caused Devils Lake to rise rapidly over the last few decades. If the lake reaches 1,458 feet (444.4 meters) above mean sea level, it will naturally overflow into the Sheyenne River, a tributary of the Red River. The North Dakota Geological Survey has determined that the lake has probably overflowed into the Sheyenne River only twice in the last 4,000 years.

These Landsat images clearly show the lake’s dramatic change. In 1993, the lake water level was 1,422.6 feet (433.6 meters) above mean sea level. The lake reached an all-time high of 1,454.4 feet (443.3 meters) above mean sea level in June 2011. In 1993, the lake covered about 44,000 acres (17,800 hectares)—it has expanded to over 211,000 acres (85,400 hectares).

Even though it is still a few feet from its overflow level, the lake’s rapid rise is a great concern for residents of the region. If the lake does reach its overflow level, natural flooding could cause considerable damage downstream. The loss of farmland caused by the rising water has already been devastating to local farmers.

Another concern is algae blooms. The 2018 images show blue-green algae discoloring the water. In a severe algae bloom, the water can resemble spilled green paint or green pea soup.

How is Las Vegas getting enough water for its expanding population? Most of it comes from Lake Mead on the Colorado River. The Colorado River provides water for Las Vegas, as well as Phoenix, Los Angeles, and San Diego. As the populations of all of these cities continue to grow, water demand also increases. However, less snowpack in the mountains in recent years has reduced the river’s flow and thus the amount of water stored in the reservoir.

Landsat images starting in 1972 show the changing water level of the lake. U.S. Bureau of Reclamation records show its highest level was in July 1983, when it was 1,225 feet above sea level. In July 2022, Lake Mead’s water level fell to 1,041 feet. The level hasn’t been this low since the lake began filling in the 1930s. In November 2024, the lake was reported to be 33% full.

The drop in lake level isn’t even as apparent as it might otherwise be because of the steep topography in the region. Lake Mead is inside a canyon environment, so the drastic reduction in lake level does not equate to as drastic of a reduction in surface area, even though the surface area reduction is quite noticeable.

How do those in northern winter climates get roses to their loved ones in February for Valentine’s Day? The answer is to import them from warmer climates.

Kenya offers the perfect climate for flowers year-round. Its floriculture industry covers land near a shallow lake near the equator. Lake Naivasha is one of the few freshwater lakes in East Africa. Its depth varies from 2 to 8 meters, and the surface area as shown in the 2023 Landsat image is about 150 square km.

Direct rainfall on the lake and three rivers feed freshwater to the lake. The Gilgil and Malewa are perennial rivers, and Karati is a seasonal river. The Malewa contributes up to 90% of the water to the lake. The lake has no surface outlet—it is referred to as an endorheic lake. In most endorheic lakes, salts are left behind when the lake water evaporates. That is, the salts are not washed out through an outlet to another outgoing river. Lake Naivasha, however, maintains its freshwater status because the lake water seeps into the ground, taking the salts with it.

The wetland areas around the Lake Naivasha support not only the large flower industry but also fishing, tourism, and geothermal power. Hundreds of millions of dollars’ worth of cut flowers are exported from Kenya to Europe and other countries. As of 2018, Kenya has 38% of the European Union’s market for cut flowers.

The region offers steady sunlight and days that vary very little in length. Lake Naivasha is not far from Nairobi, Kenya’s capital and largest city, about 90 km away. So transport is relatively easy. The Nairobi airport has a terminal dedicated to transporting flowers and vegetables.

Still, the industry has had challenges. In recent years, workers have been laid off because of lower demand and higher costs. The increase in agriculture has put pressure on the water resources of the area, affecting the water quality of the lake.

As Phoenix grows, the need for water rises. The Salt, Verde, and Gila Rivers bring water from Arizona’s mountains, but it’s not enough for millions of people. Groundwater is pumped to the surface, but this withdrawal lowers the water table, so it’s not the best answer.

Phoenix looked elsewhere to supplement its water supply and established the Central Arizona Project (CAP). Completed in the early 1990s, this system of canals, pumps, and tunnels brings Colorado River water along 336 miles of canals to Phoenix and Tucson.

Part of the CAP is an expansion of the Waddell Dam that forms Lake Pleasant on the Agua Fria River. The New Waddell Dam was completed in 1994, and it increased the size of Lake Pleasant, which is evident in these images. Construction of the new dam can be seen in the 1991 image. 

Lake Pleasant water is only partly from the Agua Fria River. The lake also receives water from the Colorado River, over 100 miles away. A canal, which can be seen in the 1991 image, pumps water uphill from the canal to the lake in winter. During summer, when electricity and water demand is high, water is released through a hydroelectric power plant.

One drawback to this impressive engineering feat is that Arizona must share Colorado River water with Los Angeles and San Diego, California; Las Vegas, Nevada; and the irrigated fields of the Imperial Valley. Recent drought in the western United States has meant less water to go around for these large cities.

Meanwhile, urban growth continues to expand north of Phoenix closer to Lake Pleasant. In the 2011 and 2023 images, this growth is evident, including construction of a new freeway (the bright curvy line). Can you find where the new golf courses were built?

Glen Canyon Dam on the Colorado River was completed in 1963. It created Lake Powell, which ebbs and flows depending on upstream precipitation. Lately, it’s been more ebb.

Glen Canyon National Recreation Area encompasses Lake Powell and is visited by more than 2 million people per year.

Since 2000, the Colorado River Basin has been in an extended drought. During the period 2000–2018, the inflow of water into Lake Powell was above average in only 4 years. As a result, Lake Powell was at less than half capacity in January 2019—and 38% full in November 2024.

Droughts combined with a rising population means water sustainability will only become more of a challenge. In addition, hydropower capacity at Glen Canyon Dam could be reduced. Severe droughts are a regular part of the climate variability in this region; however, droughts are expected to become more severe in the future.

Many lakes in eastern South Dakota have expanded during the Landsat record that began in 1972. Lake Thompson is one that has displayed remarkable change in recent decades.

This part of South Dakota is in what is known as the Prairie Pothole Region (PPR). Numerous depressions in the land were left behind there after the most recent glacial retreat. These depressions are termed potholes and collect rainfall and snowmelt to form wetlands and ponds of varying size.

A wet period in the 1980s and several years in the 1990s resulted in dramatic filling of Lake Thompson, located about 50 kilometers west of Brookings, SD, along with other nearby lakes and sloughs. Lake Thompson is now South Dakota’s largest natural lake.

Lake Turkana, formerly Lake Rudolf, lies in the Rift Valley of East Africa. It is about 250 km long and 15–30 km wide, with an average depth of about 30 m. Lake Turkana is one of the largest desert lakes in the world, and it lies in a closed basin in northwestern Kenya and southwestern Ethiopia. These images show the delta of the Omo River, which provides more than 80% of the water to the lake. The lake has no outlet and lies in an arid area.

Ethiopia is constructing a series of dams on the Omo River. The Gibe I and Gibe II dams are completed, and the Gibe III dam began filling its reservoir in 2015. Studies are ongoing to understand the interactions between regulated flows as a result of the dams and rainfall on the water levels of Lake Turkana. Scientists use many years’ worth of data to get a better understanding of the lake’s natural variability and how that variability might be affected by dams, irrigation, and rainfall.

Lake Urmia in Iran is another closed basin lake that has been shrinking. Continuous declines in water flowing into the lake have caused a general decline in its surface area since 1995.

Water only enters Lake Urmia via rainfall and runoff from rivers flowing into it. As a closed basin lake, its water levels fluctuate with changes in rainfall. Once water reaches the lake, it only leaves via evaporation. When the water that flows into the lake is diverted for human uses, those dynamics are prone to big changes.

The lake’s southern basin is shallower than its northern basin, so recent images show the water disappearing from the southern basin first. These Landsat images use the shortwave-infrared, near-infrared, and green wavelengths of light. Because water absorbs infrared light, water (dark blue to black) contrasts with the surrounding land areas. As the water becomes shallower, light is reflected off of the lakebed in shades of light blue. Lighter blue and bright areas immediately surrounding the lake are where the receding shoreline has exposed the lake bottom.

Data from the USDA Foreign Agricultural Service shows a downward trend since the mid-1990s. However, a fresh pulse of water from rains during fall 2018 and spring 2019, along with seasonal snowmelt, increased lake levels. This increase isn’t only evident in the graph data. The 2019 Landsat image shows a rebound in water levels over 2018. The basin remained mostly filled as recently as 2019. The 2023 image shows that drought returned, bringing water levels down again.

Thousands of well pads are scattered across northwestern North Dakota. This series of images shows an example of a location with several of them. These rectangular shaped areas of land cover 4–7 acres each. The small bright shapes in the images are much smaller than agricultural fields. Cropland is larger blocks of land in varying shades of green or tan.

The parcel of land dedicated to oil pumping is cleared for setting up drilling equipment. Once drilling is completed at a location, it can then pump oil. Each pad seen in the images is a well pad with either drilling or pumping in progress.

In the entire Williston Basin, 12,990 hectares of land have been converted to well pads. The previous land cover of this area was almost entirely agriculture and prairie.

The images displayed in this section show a different way of looking at change over time. These images are part of the National Land Cover Database (NLCD), generated and distributed by the USGS EROS Center and a group of federal agencies called the Multi-Resolution Land Characteristics (MRLC) Consortium.

NLCD portrays land cover change spatially as a comprehensive “wall-to-wall” 30-meter resolution database. Its national coverage supports many different applications: fire, urban development, insect damage, mining, best practices in land management, and more.

The Annual NLCD products are available for the conterminous U.S. each year from 1985 to 2023. The legend shows which colors correspond to the different types of land cover. For example, red indicates impervious surface. This means developed, or built-up, land. Pink is less intensively developed urban areas, and darker red is more intensively developed. Urban land shows the most obvious change seen in these NLCD maps of Las Vegas.

The dominant land cover surrounding Las Vegas is “shrub/scrub,” which is shown as tan. These areas are dominated by shrubs less than 5 meters tall.

Shiyan, China, was a small village in the mountains until the 1960s. That’s when a lot of industrial production was established there in its relatively safe mountainous regions. However, because of the mountainous terrain, Shiyan did not have enough land to offer for expansion. So the industry moved away in 2003. To prevent that from happening again, the city began planning to create new land for development in 2007.

Shiyan is now a famous production base for automobiles. Dongfeng Motor is headquartered in Shiyan. Other major industries in Shiyan include pharmaceuticals, textiles, and chemicals. Shiyan is also one of the central tourist centers in the northwest of Hubei Province.

To create this new land for building, they are leveling mountaintops and filling in valleys. Explosives level the hills, and fleets of trucks haul away the soil. This rock and soil is then used to fill in the valleys.

This additional land that can be developed can ease pressure on land that is valuable for agriculture elsewhere. It creates land for cities to expand where they could not do so previously. Most of the new land is for warehouses and industry. A small amount is for housing.

The bright spots in the images show the leveled and cleared land. These areas are then quickly replaced by industrial centers.

The Sharq El Owainat airport is visible on the right side of these images. The runway appears in the 1997 image.

Landsat’s accuracy is key to other systems as well. Satellite sensors launched by other countries, cubesats launched by private companies, and sensors on NASA Earth-observing satellites benefit from the accurate Landsat calibration.

Calibration work may seem esoteric, but it makes the science application work possible. The work that solves problems couldn’t be done without the accuracy of the data. Landsat images are simply pretty pictures—until we calibrate them; then they become accurate datasets.

A sensor on the early Landsats had a name worthy of some Star Trek gadget. Originally Landsat’s primary sensor, the Return Beam Vidicon (RBV) flew on the first three Landsats.

A sample RBV image shows the northwestern coast of Madagascar. The black-and-white image from 1981 has higher resolution than the Multispectral Scanner (MSS) on board the early Landsats. So what happened to these RBV images, and are they useful today?

What’s a Vidicon?

A vidicon is a television camera tube that formed an image by focusing light onto a photoconductive faceplate. An electron beam scanned the faceplate, detecting light intensity for each scan line. The beam then bounced back by an electrically charged area. The resulting picture was made up of about 5,000 separate scan lines (compared to 525 for a traditional television picture).

Las Vegas, Nevada, is one of the fastest growing metropolitan areas in the United States. Las Vegas grew from a population of 1,375,765 in 2000 to 1,951,269 in 2010, a 41.8% increase, third highest in the country for that decade. The increase from 2010 to 2023 was almost 20%.

These images show the rapid growth of the city. The tip of Lake Mead is visible east of the city (dark area), where Hoover Dam impounds the Colorado River.

Population growth of the Las Vegas Metropolitan Area

In this area at near Lawrenceville, Illinois, and Vincennes, Indiana, some fields are green, some are maroon, and others are pink. Why are these fields different colors?

In this band combination, bright green is healthy vegetation, so the crops are growing well in those fields. Some fields have a faint green color; crops are growing in those fields, but they are younger than the crops in the bright green fields. The pink and maroon fields are bare soil, probably planted but there is no growth yet. The bright pink fields have slightly less moisture in the soil. In the post-flood image, some of these fields near the river that were flooded are dark pink, indicating they still contain moisture.

South Africa needed water. Lesotho needed electricity. One huge project aims to solve both problems.

Lesotho is a small mountainous country completely surrounded by South Africa. A little smaller than the U.S. state of Maryland, Lesotho’s most important natural resource is clean water, dubbed “white gold.” Lesotho’s highlands receive about 1,200 millimeters of rainfall annually and are the main headwaters for the Orange (Senqu) River system. Most of that water leaves Lesotho, flowing east to west across South Africa, where the river empties into the Atlantic Ocean.

Measured by per capita gross domestic product (GDP), Lesotho is a relatively poor country, falling in the bottom 20 percent of countries. South Africa is one of the wealthier countries in Africa but has been experiencing water shortages. Its industrial heartland includes the large city of Johannesburg, over 300 kilometers to the north and outside of the Landsat scenes displayed here. Recurring drought and increasing demand for water have put additional pressure on water resources there.

Two dams have been completed on tributaries of the Orange (Senqu) River as part of the Lesotho Highlands Water Project (LHWP), which harnesses Lesotho’s water and exports it to South Africa. Before this project, Lesotho was dependent upon South Africa for electricity. Lesotho can now generate electricity from the dams. Additionally, hundreds of kilometers of roads were built or upgraded in Lesotho’s mountainous landscape, cutting down on travel time, in some cases by days.

Not all of the reviews of this project have been positive. Some studies have reported there may not have been enough foresight of the stress on water resources that drought and climate change could be causing. Furthermore, reduced river flows could affect communities that rely on the river for livelihoods, and some say this impact was not well understood before the project began. Besides these possible environmental consequences, many communities claim that they did not receive promised compensation for relocation.

The Everglades sit on top of a bedrock of limestone. Limestone quarries, the dark rectangular shapes just west of the urban areas, provide about half of the rock used in Florida’s construction.

In this part of Florida, groundwater is very near the surface. So as the rock is mined, the quarry pits fill with water. These lakes range from 30 to 50 feet deep and cover a total of about 4,900 acres. Because of these artificial lakes, the region earned the name “The Lake Belt.” These rectangular water bodies expand and change shape over time in the image series.

Near the top center to the left of the highway, some of the areas that started out as mines turned into developed, with that desirable waterfront incorporated into the residential areas.

The prominent diagonal line running from the upper left to the lower right is the Miami Canal, which flows from Lake Okeechobee and into the Miami River near the airport. The river then flows through downtown Miami and into Biscayne Bay.

On the far left of these images is a vertical line that marks the boundary of the Francis S. Taylor Wildlife Management Area. Between that and the limestone pits is the Pennsuco Wetlands, part of the east coast buffer project, designed to act as a zone of protection between the Everglades and the urban centers further east. Water can be captured, stored, and released when it benefits both the urban communities and the ecosystem. Higher water levels in the Everglades then have less chance to impact the populated areas.

The prominent land feature that separates the northern and southern basins is the Lisan Peninsula. (Lisan means “tongue” in Arabic.) The geologic name for this structure is diapir, a mass of low density material that has pushed upward.

On March 22, 2000, the northern part of a salt pan on the Lisan Peninsula collapsed 2 months after it was completed. The February 15, 2000, image shows water in this pan, but in the October 28, 2000, and later images, the water is drained out. About 56 million cubic meters of brine went back into the Dead Sea when the dike collapsed.

As the Dead Sea level declines, the land that becomes exposed is unstable. Future land feature changes similar to the salt pan collapse on the Lisan Peninsula may accompany the decreased water levels and exposure of additional unstable land.

Every year, it takes one tree, 16 inches in trunk diameter and 100 feet tall, to meet every American’s need for paper, packaging, and lumber products. If that tree was harvested in Oregon, it was logged using strict environmental protections.

In Oregon, the goal is sustainable forestry. The logging industry there works to meet current societal needs for forestry products while ensuring that future generations will be able to enjoy the same benefits from abundant forest resources that we do today. Much of Oregon has been heavily logged in the past, but in western Oregon, where these Landsat images are focused, nearly 1 million acres of intact, old growth forests remain. And almost all land in Oregon that is logged is reforested.

One reason for the goal of sustainable forestry in Oregon is the Northwest Forest Plan, adopted in 1994, which resulted in a decline in forest harvesting on federal lands. After the plan was implemented, harvesting rates became longer to accommodate regrowth, and more partial cuts were used instead of clearcuts. The plan also works to protect old growth forest while maintaining sustainable logging.

A multi-image time-series from Landsat can create “regrowth trajectories.” The 30-m resolution from Landsat is enough detail to see the harvest rotation cycle. Douglas fir in western Oregon can regrow to a closed canopy stage in 15–20 years, so the time frame of the Landsat record can show just over one harvest rotation cycle.

Even from one year to the next, there is change. For example, look closely at the recent images. Can you find new cleared areas in the green forest land?

These close-up images show a portion of the reserve. The red spots in the global forest map indicate forest loss. The area in the center of the image is in a location called Lomas de Aparicio, which is within the core zone of the reserve. The forest loss here has been identified as large-scale logging activity by Vidal and others (2013) and by Google Earth imagery from 2004 and 2013.

All of these images clearly demonstrate that the forest was heavily impacted between 2004 and 2013. It is unlikely monarchs will form overwintering colonies at the Lomas de Aparicio site in future years. If they do, they will face much greater environmental risks during their overwintering stay.

Even though the monarchs use only a small portion of this oyamel forest habitat, they depend on the entire dense forest structure. The forest canopy acts as a blanket and keeps them warmer and captures moisture that they need for their survival. A fragmented forest will not do this.

Looking at a more specific region within these images makes it clear that that the Spiny Thicket seems to be disappearing fast. Since 1990, this ecoregion has had the highest deforestation rate in the country.

Agriculture in this region is done by slash-and-burn. The fields are cleared by burning, then planted.

The forest is also used for charcoal production. Most households use charcoal to cook their daily meals. Even though this is less destructive than slash-and-burn, charcoal production causes the degradation of vast areas of the Spiny Thicket. Even when the Spiny Thicket regenerates, it does so as cactus scrub.

Landsat is uniquely suited to monitoring these types of land changes over large areas. Forests once covered Madagascar, but forest cover has been reduced to less than one-fourth of the island’s original extent. Information gathered by Landsat can help improve management of remaining resources.

Madagascar, the world’s fourth largest island, is located off the southeastern coast of Africa in the Indian Ocean. Because it is isolated from neighboring continents, almost all of its plant and animal species are found nowhere else on Earth.

In southwestern Madagascar, plants have adapted to a dry desert-like climate. These unique plants are so peculiar they cannot be classified into common classes like desert or forest. Many species there have small leaves and spines and can retain water very well—characteristics of succulents that are typical in deserts. They also have tall trunks, appearing more like trees. So the vegetation in this region often is named Madagascar Spiny Thicket.

This ecoregion, which extends across southern and southwestern Madagascar, has a long dry season. Most of the rain falls from October to April, but rainfall amounts can be erratic. The plants’ unusual adaptations allow them to survive the long dry periods. But this ecoregion is experiencing rapid deforestation, which is evident in this Landsat series.

In the Amazon basin, some rivers run wild. With no dams or levees to control them, they are free to meander—some more than others.

For example, the Rio Mamoré, which flows north across Bolivia, is one such wanderer. It flows from the Andes Mountains and across the Bolivian lowlands into Brazil. Watching this river meander in Landsat images over the past few decades shows us how much a river can meander under natural conditions. The Mamoré has a large sediment load, so it meanders more than most.

These meandering river dynamics are important for maintaining a healthy habitat. The floodplains here depend on the river migration to maintain the wetland habitats.

The growing city of Trinidad, with a population of over 100,000, can be seen in the upper right of these images, just east of the river.

Bahrain’s capital is Manama, a city with an estimated population of 1,480,000 in 2017, up 1,567% from 88,785 in 1971. Expansion into the desert and onto artificial islands is evident in this series of Landsat images.

The amount of vegetation (green) clearly increases in the past few decades. The added vegetation is mostly agricultural or in heavily landscaped areas. Near the bottom of the image, the addition of a golf course is seen in 2001, which is expanded by 2015. To the left of that is a road that has been lined with vegetation by 2015.

The Bahrain International Airport, with its 3,418-meter runway, is prominent in the upper right corner of the image. Other notable industry in Manama is the addition and expansion of the Arab Shipbuilding and Repair Yard, which has 15 ship repair berths, and Khalifa bin Salman Port, which opened in 2009 as a major regional distribution center. Both the shipyard and port are on reclaimed land east of Manama.

Mangroves are sturdy species. They can recover from storm disturbances relatively quickly. They can tolerate salt water, saturated soil, high wind, and storms. But they are a threatened ecosystem because of overexploitation of its resources.

Mangrove forests appear bright green in the Landsat images. Their degradation is evident in the reduction of the green color throughout the series. One island remains bright green amid the deforestation. That’s the Meinmahla Kyun Wildlife Sanctuary, which was established in 1986.

Mangroves offer a multitude of benefits, both for the environment and for people. As guardians of the shoreline, mangroves reduce the impacts from storms and tsunamis. Their dense and partially submerged root system protects inland areas from erosion and flooding.

Food security is closely linked to a healthy mangrove ecosystem. A mangrove delta is a nursing ground for aquatic species, which provide food for local communities. Besides providing fuel wood and building material for people, mangroves also purify the water.

Mangrove ecosystems have a global benefit, too. Worldwide, mangroves sequester an estimated 22.8 to 25.5 million metric tons of carbon each year. A mangrove region as extensive as the Ayeyarwady Delta is well worth monitoring.

The lahars produced by Pinatubo’s eruption blocked the flow of the Mapanuepe River and created a new lake, named Mapanuepe Lake. The formation of the lake flooded the small towns of Aglao, Buhawen, and Pili. Breakout lahars continued to be a threat in the years after the lake formed, but artificial channels help to stabilize the lake’s water level.

In the series of images that accompany this section, Pinatubo’s summit crater is in the upper right corner. In the 1989 image, the maroon colors indicated moisture in the soils southwest of Pinatubo’s summit. After the eruption, the bright gray or pink colors streaming from the summit are sediment-laden lahars in the Marella River, which flows into the Santo Tomas River Valley. The lahars effectively widened this river plain, and the sediment persists, indicated by the shades of pink. The brighter mottled white and gray in the upper left of the image after the eruption gradually returned to forested green tones.

Mapanuepe Lake is the dark shape in the lower right. Southeast of the lake is the copper and gold Dizon Mines. Cleared land for the mining activity appears in pink shades in the midst of the green forested areas. The small dark shape is water at the bottom of the mine’s main open pit.

Again, a few ASTER images in this series help fill in some gaps where Landsat imagery was cloudy. The complementary imagery of the changes over time to these valleys help scientists understand more fully the trajectories of the changes.

Maui, the second largest Hawaiian island, is made up of two dormant volcanoes, West Maui Mountain and Haleakala. Between those peaks lies Maui’s central plains, which for decades were dominated by sugar cane fields.

The sugar industry in Hawaii dates to 1835 with the establishment of sugar plantations. Sugar cane was a major crop and economic contributor for Hawaii through the 20th century.

When the island’s last large cane mill closed in 2016, 41,000 acres of cane fields began changing to nonnative grasses, which are susceptible to fire.

Landsat is tracking this shift—through the sporadic cloud cover in the tropical paradise—from the bright green shapes that dominated the central plain of the island to the grasses that took over. Dry grasses appear as a brown swath, but the grass greens up in winter, as seen in the January 2022 image. The green grasses are a different shade and pattern than when the land supported sugar cane.

Landsat images show chunks of ice floating on the surface of the water as Columbia Glacier retreats. These icebergs have broken off, or calved, from the front edge of the glacier. This conglomerate of floating ice and chunks of icebergs is known as an ice mélange, which can slow the rate that glaciers slip into the sea.

The ice mélange looks less defined in the images than the glacier itself, which usually has some smooth-looking longitudinal lines. The mélange appears more mottled, and in some images there is very little of it at all (like in 2006). So don’t confuse ice mélange with the end of the glacier.

Columbia’s terminal moraine is still evident long after the end of the glacier retreated far upstream and serves as a marker for the maximum advance of the glacier. A terminal moraine is the accumulated mass of sediment, rocks, and debris that the glacier deposits at the terminus. The moraine at this historical terminus prevents the mélange from drifting beyond it.

View an animation showing more Landsat images of Columbia Glacier.

The boom times of iron ore mining in northern Minnesota are long gone, but mining operations continue and are even expanding, as seen in these Landsat images.

The Mesabi Range, which stretches 80–100 miles from Grand Rapids to Babbitt, contributed about 60% of the total iron ore output in the United States throughout most of the 20th century. The soft ore was close to the surface, and it could be scooped from open-pit mines and shipped by rail to Lake Superior and eventually to steel mills.

Iron ore production peaked in the 1940s when more than 600,000 tons were shipped during World War II. Production remained high in the postwar years and then declined. The high-grade ore was soon nearly depleted. Mining activity on the Mesabi Range now involves digging out lower grade ore for processing.

The iron ore open-pit mines on the Range are among the biggest in the world. But the footprints of the mines’ tailings ponds are even bigger. Both are readily visible in these Landsat images.

Fifty years of observing the Earth means Landsat has witnessed many land surface changes. A few of those changes are shocking in their sheer scale and swiftness.

A vast wetland in southern Iraq has been decimated in recent decades by a variety of factors—all documented by the consistent and objective data from Landsat satellites.

Imagery from Landsat’s first few weeks of operation in summer 1972 shows the Mesopotamian Marshes at nearly their maximum extent. Over time, Landsat shows the marshes diminish, dry up, and then partially recover.

The Mesopotamian Marshes are divided into three areas: Al Hammar, Central, and Al Hawizeh.

What looks from above like a temporary geoglyph on the ice or a series of abstract Etch A Sketch doodles are ice roads on Mille Lacs Lake in central Minnesota. The ice roads provide a way for ice fishers to get to their ice shacks on the frozen lake. Some roads extend for a few miles.

Even though Landsat is famous for its 50-year record of global land change, its observations can show us how temporary villages and ice roads change over time on a large frozen lake.

The winter of 2023-24 was uncommonly warm in Minnesota and brought lower than average snowfall. And the Landsat imagery shows it. The 2024 images show a stark difference to the other images. 

The open-pit copper mine in Chile's northern Atacama Desert has a tailings impoundment to conserve water and minimize environmental impacts. Landsat images show the expanded impoundment. The tailings material is left over after the majority of the valuable metals have been removed from the ore.

This copper-bearing waste is poured into the impoundment area as a liquid (dark region at the bottom of the 2011 and later images); it dries to the lighter-toned spoil seen in the images. The spoil is held behind a retaining dam, just more than 1 kilometer long, visible in the 2011 and later images as a straight line on the northwest corner of the pond.

As part of the mining, huge amounts of material are dug up and removed. The ore is crushed within the pit, and conveyors bring the ore to the mill.

New pits open up as the time series of Landsat images progresses. Landsat shows not only the expansion of the mining pits but also the extent of the material piled up alongside the pits.

The shifting shape of gray and blue on the right is the Talabre tailings impoundment. The Talabre is a natural depression, and the tailings, the materials left over after the ore is extracted, are dumped into several basins. The basins are separated with dikes, and the impoundment is bordered by dams, all made with dry tailings.

An underground mining operation is now underway. Testing indicates that 2.3 billion tons of copper ore lie below the open pit. Underground mining began operations in 2019.

Landsat satellite imagery shows the oil sands region of Northwestern Alberta, Canada, expanding over the last three decades.

Getting oil from oil sands is fairly straight-forward. But that doesn’t mean it’s easy.

Near Fort McMurray, the oil sands are less than 75 meters (246 feet) from the surface, close enough for surface mining.

Surface mining techniques require the forest to be cleared. The soil and rock above the oil sand (overburden in mining jargon) is then removed. This creates the maroon or gray irregularly shaped open pit mines seen in the Landsat images. The open pits are created in a series of benches, or steps, that are 12–15 meters (39–49 feet) high. Huge hydraulic power shovels dig the oil sand and drop it into trucks that have a capacity of up to 363 metric tons (400 tons). The trucks haul the oil sand to a facility that separates the oil and sand.

The oil sand mixes with hot water to form a slurry. In this slurry, the sand settles to the bottom, clay and water sit in the middle, and the bitumen floats on the top. The bitumen is skimmed off the surface and the rest gets pumped to tailings ponds, also visible as the large blue shapes in Landsat images, often outlined in tan.

Appalachian coal lies underground in thin seams, too thin for underground mine shafts. The only way to extract the coal profitably is with surface mining.

Surface mining involves the removal of soil and rock (overburden in mining terminology) with explosives and heavy machinery to get at the coal. As much as 200–300 meters of overburden is removed. The removed material, also called mine spoils, is used to reconstruct the area after mining operations are done. The removed material takes up more volume and cannot simply be replaced (try digging a hole in your backyard and filling it back in and you’ll discover how this works).

The “excess spoils” must be dumped elsewhere. In Appalachian mountaintop mining, the excess is deposited into valleys. These valley fills are usually located next to—often downstream from—surface mines, burying headwater streams completely. The groundwater and surface waters from the mine often flow through these valley fills before discharging into streams.

Disturbed land is pink in these close-up images of a large mine about 20 miles southwest of Charleston, West Virginia. The natural color image from Sentinel-2 shows more detail in the same area. Active mining is bright in this Sentinel-2 image, and lighter green shades show some reclaimed land.

Scientists have been tracking the distribution of the mangrove forests in the Ayeyarwady Delta using satellite observations dating back to the 1970s. The change map shows when and where mangrove loss occurred. Green indicates current mangrove forest as of 2005. However, red dominates the map, which means that much of the mangrove loss occurred during the 1990s.

Unlike the Katse Dam, the Mohale Dam does not generate power. Instead, it was built as a backup reserve to the Katse Dam and reservoir. The dam was built on the Senqunyane River, another tributary of the Senqu/Orange River. The Mohale reservoir began filling by the time of the 2003 image.

The Mohale Dam is 145 meters high and 620 meters long. It is the highest concrete-faced rock-filled dam in Africa. A large basalt hill inside the basin had to be crushed to build the rock wall. The dam then formed the 21.2-square-kilometer Mohale reservoir. A 32-kilometer tunnel brings water from the Mohale reservoir to the Katse reservoir.

Before these two dams were constructed, Lesotho had to depend on South Africa. The country has now attained self-sufficiency in electric power generation. Future phases of the LHWP include construction of more dams, tunnels, and hydropower stations.

The patches of red in these false-color Landsat images are the forests where monarch butterflies spend the winter. Starting in late summer and fall, monarchs in the United States and Canada migrate south to Mexico.  Some travel up to 3,000 miles. The delicate insects are capable of flying 50–100 miles a day.

Cold weather drives the monarchs to head south to hibernate for the winter. They head for the only habitat suitable for their hibernation, oyamel fir (Abies religiosa) forests. These forests grow in only small areas of mountain tops in central Mexico, about 3,000 m above sea level. The monarchs usually cover whole trees as they keep each other warm. The short needles of the oyamel fir allow the butterflies to cluster together better than they could on flat-needled cedars or long-needled pines.

The oyamel forests provide a microclimate for the butterflies. Temperatures stay above freezing. If the temperatures were lower, the monarchs would have to use their fat reserves. The humidity provided by the forest also keeps them from drying out.

The monarchs stay in Mexico from about November to March. In the spring, they fly back north. On the way, they lay eggs on milkweed. These eggs hatch into caterpillars, who devour the milkweed leaves, then metamorphose into monarchs. These monarchs live about 5 weeks or so.

What’s especially amazing about the monarch migration is that not all monarchs take part in the journey. And unlike birds and whales, the monarchs that do complete the migration only make one round trip.

The great-grandchildren of the overwintering monarchs migrate south the next fall, somehow landing at the same trees as their ancestors. Without the use of maps or satellite imagery! 

The good news about the monarchs is that they are a beloved bug. Kids in classrooms nationwide capture the caterpillars and watch them transform into a chrysalis and eventually a monarch, learning all about life cycles along the way.

Increases in the area occupied at the overwintering sites are encouraging, but researchers continue to keep an eye on breeding habitats—milkweed restoration from Texas to Minnesota is key.

A recent study indicates that people would be willing to donate or buy nectar plants and milkweed to help preserve the monarchs’ habitat in their non-wintering locations. The willingness of Americans to buy nectar plants and milkweed could potentially be a multimillion dollar industry. Diffendorfer and others (2014) estimated that Americans are collectively willing to pay $933 million for nectar plants and $473 million for milkweed. That seems like a good start for the monarchs on their long journeys.

Monomoy is the southernmost barrier island in this system. It once consisted of North Monomoy Island and South Monomoy Island. Storms, high winds, tide, and surf endlessly change the island. The Landsat imagery shows South Beach Island migrating southward to join Monomoy, which is now considered one island. All of Monomoy Island (North and South) are designated as Monomoy National Wildlife Refuge.

In the years since European settlers began making coastline maps, the changes to all of these islands and beaches have been observed in fairly predictable patterns. The dilemma now, with an increasing population, is to monitor how storms, flooding, and shoreline erosion affect property and both human and wildlife populations.

Play this animation to see the change in this area from 1984 to 2018.

The busy port city Mopti is located at the confluence of the Niger and Bani Rivers. It is a crossroads of trade between the north and south.

Farming in this region relies on rainfed cereal crops. This makes farmers vulnerable to weather-related risks. They experience only one good harvest out of every three rainy seasons. To help residents plan for high or low water flood seasons, scientists are working on a greater understanding of the hydrology of the delta.

The Niger and Bani Rivers determine the flood extent each year. The water level in Akka, toward the northern part of the delta, can be reliably predicted from the combined flow of these rivers.

Flood forecasts will become increasingly important as the population grows and as pressure on water resources increases. Water level measurements and satellite images help predict the onset of seasonal floods and help achieve food security. An early warning system will help predict drought and monitor food security. Data from both on the ground and satellites help manage water resources.

The flooding that happened in summer 2008 in Indiana and Illinois started late in 2007 with above normal snowfall. This extra snow saturated the ground as it melted in spring 2008. The above normal rainfall in the spring only made the situation worse. (Many U.S. Geological Survey streamgages in the region already showed stream levels at higher than average streamflow.) The heavy rainfall event on June 6–7, while by itself might not have caused catastrophic flooding, combined with the saturated conditions from the previous winter snows to cause this flood.

On June 6, 2008, a nearly stationary (unmoving) weather front was draped across south-central Indiana, and moisture from the Gulf of Mexico streamed north to fuel thunderstorm development. Nearly continuous thunderstorms over a 12–16 hour interval dumped significant amounts of rain on the region. This rain flowed into the already high rivers and streams, which rose quickly.

In the precipitation map on the left, the colors indicate the amount of rainfall for the first half of June 2008. The colorful area from eastern Illinois and into central Indiana reflects the heavy rain that occurred there at that time.

• Green = less than 4 inches
• Yellow to orange to red = 6–12 inches
• Violet to white = 12 inches or more

Within the Inner City, the moats and walls of the Forbidden City (Imperial Palace Museum) are prominent, with Wu Gate at the southern end. Also within the Inner City are six lakes, including Zhong Hai Lake just west of the Forbidden City.

In the Outer City three parks are visible, of which the middle is the Temple of Heaven. These are the red areas (darker than the agricultural vegetation outside of the city).

In the out zoom, Kunming Hu Lake is visible on the northwest edge of the city. The historically significant Summer Palace is on the shore of this lake.

In the north-central part of the 2013 image, a few bright spots appear that aren't in the other images. This is the Olympic complex that was built for the 2008 Summer Olympic Games, and includes the Olympic stadium, which came to be known as the Bird's Nest.

An image from 1967 was acquired by the U.S. Gambit high-resolution space reconnaissance program. Part of a large collection of imagery declassified in the 1990s, the Gambit image shows fine detail, 2-4-foot resolution, of the Inner City area.

The surface of the Earth is always changing. Some changes like earthquakes, volcanoes, floods, and landslides happen quickly and other changes, such as most erosional processes, happen slowly over time.  It’s often hard to see these changes from ground level. A much broader view is needed, and multiple views that provide a record of change over time are especially helpful. Earthshots shows you how satellite data are used to track these changes.

The Landsat series of Earth-observing satellites has acquired data for monitoring the planet’s landmasses since 1972. The vast archive containing millions of Landsat scenes is managed at the U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center in Sioux Falls, SD. The images displayed in Earthshots are examples of Landsat data that help scientists worldwide understand more about how both people and nature are changing the landscape.

Each Earthshots page features a different location from around the world and explains the changes that the satellite images reveal. For example, the Mount St. Helens page shows what the mountain looked like before and after the 1980 eruption. Furthermore, it shows recent images that demonstrate how the forest is recovering. The images at the left are three of the Landsat images from that page.

Since its launch in 1999, Landsat 7 has not again seen such nice vortices over Selkirk Island. A single vortex formed on March 25, 2000, from a similar southerly wind, but then the pattern broke up. That morning the clouds were too unstable, as shown by the turbulent convection cells in the northeast.

In its first year of acquiring images, the whole island was never visible to Landsat 7. Even on a clear day like November 18, 1999, the island's heat and elevation heave up damp marine air into the cold, until it reaches its dew point and condenses into a kind of permanent parasol of clouds. This sometimes trails downwind a short distance on windy days, as on February 22, 2000.

On November 10, 2008, the island looked a bit more like an icebreaker ship plowing through ice pack; no vortex street this time, but the effect the tall mountain island has on the clouds is clearly demonstrated. The February 14, 2009, image almost displays a vortex, but it didn’t quite form completely.

These images show the famous “snows of Kilimanjaro” in 1976, 2000, 2010, 2013, and 2019. Mount Kilimanjaro, almost 20,000 feet above sea level, is the highest peak in Africa. Though only about 200 miles from the equator, it has been capped by glaciers and snow for 11,000 years. This white cap shrinks and grows almost daily, but over the last century or more, its overall trend has been a steady decline. These images show durable, hard-ice glaciers, as well as the ephemeral snow on and around them. Scientists have focused on the glaciers, trying to understand why they are shrinking, how long they may last, and what they can teach us about the atmosphere today and the Earth long ago.

In these false-color images, vegetation appears green, drylands a brownish tan, and glaciers and snow cyan.

Mount Pinatubo had likely been dormant for hundreds of years. There had been no historical records of volcanic eruptions. Local residents in this part of the Philippines hardly believed Pinatubo was a volcano, so it was difficult to convince them to evacuate once it began showing signs of an eruption throughout the spring of 1991. When it did erupt explosively on June 15, 1991, it was one of the largest volcanic eruptions of the 20th century.

The ash cloud rose 40 kilometers high, and volcanic ash blanketed the region. Making the disaster worse was the arrival of Typhoon Yunya, which hit on the same day. The heavy rains from the storm sent flows of mud and volcanic debris rushing down the mountainside in all directions. Rice and sugarcane fields were smothered. Rooftops collapsed from the weight of ash saturated with rain. Nearly all bridges within 29 kilometers of the mountain were destroyed.

Today, the mountain is relatively quiet, and about 300 meters shorter than it was before the eruption.

Landsat’s historical record reveals the changes and regrowth as it happens, something that can’t be witnessed from the ground. Furthermore, images from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor on NASA’s Terra satellite add more information about the changes to the mountain and surrounding region. Data from these satellites can help us analyze a larger area in a much shorter amount of time than ground surveys, providing valuable information for local decision making.

Another set of close-up images shows the area around Mount Rushmore National Memorial. The same pattern is apparent here—a decrease in green forest cover surrounding this popular tourist attraction. 

Landsat is well suited to studying tree mortality over large areas. The Landsat record covers a long time period. Its infrared wavelengths help make forest disturbance events easier to detect. In most regions of the United States, Landsat provides several clear images per year, which can be useful for tracking the spread of the infestation. Best of all, Landsat data is freely available.

Monitoring a large-scale epidemic like this one is aided by the comprehensive coverage of Landsat imagery. Because field plots are expensive to implement over large areas, Landsat provides forest managers an affordable way to pinpoint where to break up stands of infested trees to try to minimize the spread and reduce fire risk.

The dense historical record that Landsat provides is also important because in some areas, other disturbances such as fire can obscure evidence of past disturbances. For example, the upper right of the 2002 image shows a maroon burn scar from a recent wildfire. Landsat enables scientists to better study the historical interaction between pine beetles and other types of disturbances which occur in complex landscapes.

These images show the area around Mount St. Helens, in southwestern Washington, before and after its eruption of May 18, 1980. In these false-color images, forest appears as bright red interspersed with patches of logging. Snow appears white, and ash is gray.

The cities of Vancouver, Washington, and Portland, Oregon, are visible in the southwest of the zoomed-out images, north and south of the Columbia River, respectively.

Mountaintop coal mining is a major cause of land cover changes in the central Appalachian Mountains of the eastern United States. The landscape disturbance mountaintop mining causes is different from others (such as forestry, urbanization, or agriculture) in that it can extend deeply into the ground, disturbing even the bedrock. Landsat imagery from the 1970s has catalogued the changes.

These false color images show the natural landscape of the area: forested mountains are bright green, and numerous streams and valleys give the land a wrinkled appearance. Mining areas are pink, and reclaimed mining land is usually light green.

The reason for the large-scale change caused by this type of mining is that one ton of coal is extracted for every 16 tons of terrain displaced. In the mountainous Appalachian landscape, the displaced material ends up in river valleys. More than just the look of the landscape changes—the drainage network itself is altered.

First mined in the 19th century, low-sulfur Appalachian coal can be extracted relatively cost-effectively by the mountaintop removal process. This method allows almost all of the coal in a seam to be removed. Understanding the hydrologic changes brought on by this mining practice is key to the future of the communities in the region.

The town of Chuquicamata was established as a mining camp when mining operations opened. After much mining and open pit expansion, the town ended up being too close to the mining operations. Dust from the mine and gases from the nearby smelting plant caused the mining company to relocate the entire town.

Besides the health and safety concerns, the company was running out of convenient places to pile up mine waste. To extract 1 kilogram of copper, 100 kilograms of rock has to be removed from the ground. That waste material has to go somewhere. So now, the site of the former town is beginning to be buried in mine waste.

Most of the town has not yet been buried and stands as a ghost town. Residents were moved to Calama, a city about 15 kilometers away. Codelco, the government company that owns the mine, built over 5,000 homes—one for each family. Residents began moving in 2004, and by September 2007, Chuquicamata was officially abandoned.

The Landsat images show the location of the former town and the piles of mine waste encroaching on its north side. An image from Europe's Copernicus Sentinel-2 satellite zooms in closer with finer resolution to show the location of the town in more detail.

Despite its problems, RBV data has been used in land change studies.

RBV data was used in a recent scientific study of glaciers in Turkey. Scientists used RBV images from 1980 (along with dozens of other Landsat images and high-resolution commercial satellite images) to document the areal extent of all glaciers in that country. The researchers noted that RBV’s higher resolution was an excellent source for glacier studies.

The glacier covering the top of Mount Ararat is Turkey’s largest glacier. Based on data from the RBV and more recent Landsat sensors, the glacier area of Ararat diminished from 8.9 square kilometers in 1977 to 5.6 square kilometers in 2008, according to the study. Most loss took place on the southern, western, and eastern sides of the mountain.

Even though RBV had an impressive spatial resolution, the near-infrared and shortwave infrared imaging capability on current Landsats defines the extent of ice more clearly than RBV could.

The depth of the Landsat archive across the history of Landsat sensors made this study possible. It’s important to continue to monitor these glaciers and gauge the effects of these changes, and RBV turned out to be an excellent source where data did not already exist.

These images show shifting strip mines in eastern Ohio, from 1973 to 2022. In these images, the mines appear as bright spots against the green forest background in the southern part of the images.

The Muskingum mines were started in the 1950s in Muskingum County, Ohio, and are now operated by the American Electric Power Company. The bed of coal being mined, known as the Meigs Creek coal, is about 60 inches thick, of intermediate grade, and is part of the Monongahela geologic group, deposited about 300 million years ago.

At that time, central Ohio was covered by a shallow inland sea, with a floor of limestone and sandstone. Then, to the east, the Appalachian Mountains slowly pushed upward. Streams flowed off the mountains into this inland sea, dropping sediment and creating deltas along the coast in what is now eastern Ohio. Swamps grew on these deltas, and conditions were just right for the dying plants to form layers of peat. Over the years this peat was buried by more sediment (the sandstone and shale we now see covering the coal), transforming the peat into coal through heat and pressure.

Southeast of Shanghai is an area of major land change where a planned city is being built. Nanhui New City covers about 74 square kilometers and is intended to provide space for 800,000 people. It was formerly called Lingang New City and was renamed in April 2012.

The main feature of the new city is a circular artificial lake, visible in this series of images starting in 2004. Dishui Lake is 2.5 kilometers across and includes three artificial islands. The concentric structure of the city resembles a compass rose. The streets radiate out from the center. Waterways extend all over the city to support its theme of “waterside living.”

Off the coast is Yangshan Deep-Water Port, one of the largest shipping ports in the world. The huge port opened in 2005 and can handle the world’s largest container vessels. More than half of Yangshan Port was built on reclaimed land.

The port connects to Nanhui New City by the Donghai Bridge. Construction of the bridge is visible in the 2004 image. It opened to general traffic in 2005. The 32.5-kilometer-long bridge carries six lanes of traffic and is one of the longest bridges in the world.

As rain falls through the sky it absorbs carbon dioxide, making it slightly acidic. All stone is subject to this acid, but limestone dissolves especially rapidly, and its cracked, fractured structure lets the water seep down through it. Over many years, elaborate networks of tunnels and caves form underground, often with a honeycomb of vertical “pipes” that drain the area underground, rather than through ordinary streams and rivers draining laterally to the ocean. Karstic areas have few streams. Other features of a karstic landscape are artesian springs, underground rivers, natural bridges, caves, quicksand, and especially sinkholes.

A sinkhole forms when the roof of an underground cave collapses and the rock and soil above it drop down to fill the void. Sinkholes occasionally make the news by swallowing buildings, roads, and trucks. Since water often lies just below the ground in Florida, these sinkholes often fill with water. This is why these Landsat images show so many lakes; Florida has over 7,000 lakes larger than 10 acres and many more smaller than that. Sometimes part of a lake floor will collapse—a sinkhole under a sinkhole—and the lake will drain down into the aquifer, like pulling the plug in a bathtub. You can see some good examples of karstic lakes in these images. They often have a round shape, steep sides, and no streams leading in or out.

Disney World and Epcot are labeled in these images. Epcot, located southeast of Disney World, is missing in the 1973 image and partly completed in 1986. The expansion of Epcot can be seen throughout the rest of the series of images, along with the growth of residential areas southwest of Orlando.

Subtle changes in vegetation are sometimes difficult for us to see when just looking at the imagery. The Normalized Difference Vegetation Index (NDVI) uses the difference in Landsat’s red and near-infrared reflectivity to assess vegetation health.

The graph below shows how NDVI significantly decreases in two areas of disturbed vegetation (red symbols) relative to undisturbed sites (green symbols) within the oyamel forest. The site locations are shown on high-resolution imagery in the second figure. The NDVI data can help determine if a given area is suitable to monarch overwintering.

NDVI analysis done by Birgit Peterson, scientist with ASRC Federal InuTeq, contractor to the USGS EROS Center.

These close-up land cover maps show the water level changes to western Lake Mead. The water classification (blue) diminishes as the lake shrinks through the time series.

Golf courses show up as developed land. Even though they have vegetation (as indicated in the Landsat images as bright green), here they show up as developed, open space. This faded pink color is also used to indicate lawn grasses in large-lot single-family housing units, parks, and other vegetation planted for aesthetics.

The dark red is urban areas, and in the lower center of the image is Boulder City, Nevada. The faded pink is conspicuous as golf courses, but another pink and red line traces toward the left—a highway that leads from Boulder City to part of Henderson. Around Lake Las Vegas are more golf courses and development in the upper left. The River Mountains occupy the tan space to the left of Lake Mead.

As Cairo and other urban areas on the Nile River Delta grow, new satellite cities are being constructed in the desert. Roads spread across the desert in the Landsat images, and red indicates vegetation.

Development of New Cairo City east of Cairo began in the early 1990s to help relieve congestion in the large city.

Farther east, about 35 km from the Nile, is a city being built from scratch. Designed to accommodate 6.5 million residents, this new administrative capital for Egypt will house government buildings, foreign embassies, and major companies. A monorail will link the new city to Cairo.

Construction of the all-new city began in 2015 and full completion is planned for 2050.

Construction started on Hamad International Airport (HIA) in 2004 with a huge land reclamation project. Sand from the seabed was used to build new land off the coast. More than half of the area of the new airport is on 28 square kilometers of reclaimed land.

The new airport’s two runways are 4,850 meters and 4,250 meters long. They were designed to accommodate the Airbus A380, the world’s largest passenger jet.

The first flights at HIA began in 2014. The new airport replaces the old Doha International Airport, located just west of the new airport. HIA is 12 times the size of the old airport. Indeed, its presence now dominates the Landsat images of Doha.

A major development in this time series of images is Denver International Airport. A massive piece of infrastructure, the airport sits on 34,000 acres of land, making it the second largest airport in the world. Located 23 miles northeast of downtown Denver, the airport was the fifth busiest in the U.S. in 2017.

Its footprint on the landscape is impressive, and the airport even has room to expand. Prepared for plenty of future growth, there is enough space to expand it from 6 runways to 12.

Construction began in 1989, and the disturbance to the former farm and range land can be seen in the Landsat image from 1990. The transformation from agriculture to developed land use was complete soon after, and the airport’s first flight took off in 1995.

That first year, the Denver airport serviced 31 million passengers. In 2018, 64.5 million passengers traveled through the airport.

The runway layout was planned to be as efficient as possible. None of the runways intersect. And there is enough space between them to accommodate simultaneous landings even in poor weather. This plan reduces delays and minimizes the risk for aircraft traffic jams.

Five of the runways are 12,000 feet long. The sixth was a more recent addition. Brought into service in September 2003, this runway is 16,000 feet long and 200 feet wide. That’s about 2 Landsat pixels wide, but it shows up clearly in the imagery because it’s 162 Landsat pixels long. It’s the longest commercial runway in North America.

The extra length is needed in Denver’s high elevation. Particularly for departures, larger, heavier planes need the additional space to get off the ground.

Nouakchott’s airport is visible as the straight diagonal line near the city’s center in the images in the other subsections. Over the time series of images, the airport became surrounded by the urban growth.

A new larger airport, Nouakchott-Oumtounsy (NKC), opened in June 2016. In the 2013 image, the airport is still under construction, and in 2011, there is no sign of it. Located about 20 km north of the old airport, and about 17 km north of the northern extent of the city, this new airport will accommodate even more growth.

Cutoffs are common on meandering rivers like the Wabash, but it’s rare to be able to witness a cutoff forming as it happens. Scientists are using this cutoff as a chance to learn more about what happens when these cutoffs develop and how cutoffs change after they form.

Continuous testing of the seabed and water takes place during and after construction of each phase of the Sea City project to monitor the condition of the sea and coast. Scientists take water and sand samples from many locations to monitor water and sediment quality.

Marine life is now flourishing in what was once relatively lifeless desert. Even new coral is growing in the lagoons. According to a study conducted in the new marine environment, over 1,000 marine macrobiota, including 100 commercial fish and shellfish species, inhabited the waterways within just a few years of bringing seawater to the desert. The species richness after just 4 years was equivalent to that of the open sea.

Mangroves, a salt-tolerant plant, are raised in nurseries and then planted on islands in the new lagoons. The mangroves provide nurseries for fish and stabilize the marine bed. Since the waterways are semi-enclosed, they provide protected nurseries for fish, shellfish, and other wildlife. Bees were also introduced to pollinate the salt-tolerant plants. The aim is to have a coastal landscape that can survive without freshwater.

A breakwater also needed to be built. This detached breakwater was built with 28,000 hexagonal concrete blocks, which were cast on site. These were used instead of rock because rock would not have been strong enough to protect the city and its lagoons from the currents of the open Gulf.

The new marine environment created is the heart of the project. Sea City is becoming at once a thriving ecosystem and a modern city.

The harvest of sugar cane continued through 2016, but no new planting took place. And with irrigation halted, the only growth after that is some resprouted cane and dry, nonnative grass.

Mahi Pono, a farming company, bought the land in 2018 and plans diversified agriculture for the 41,000 acres of former cane fields. Some crops are planned for export, such as citrus, coffee, and macadamia nuts. But since Hawaii imports about 90% of its food, the company’s goal is to keep most of the food it produces in the local market.

It takes time to get the varied crops up to full production, so the recent imagery continues to show the brown swath of dry grasses. For example, a plan for 40 acres of citrus trees would be the largest citrus orchard in Hawaii. But even that will not look impressive in the Landsat imagery just yet. That 40 acres would only be about 180 30-meter pixels—out of the nearly half a million pixels that make up this scene.

Furthermore, those citrus trees won’t be productive right away. The company needs to upgrade the irrigation system, recondition the soil, and wait for the trees to mature. They are also learning about what can grow in certain soils and climates. Even this relatively small area of plains between the dormant volcanoes has different microclimates and soil attributions. It takes time to recondition the land after growing one crop for so long, when decades of herbicide and fertilizer use depleted the soil’s organic material.

As of 2021, the company had planted more than 600,000 citrus trees and more than 300,000 coffee trees on the former cane land. Other trees have also been planted as wind breaks.

Lake Pontchartrain covers the northern part of these Landsat images. The curvy dark line is the Mississippi River as it meanders past New Orleans. The dark straight lines are canals, built for flood protection and as an aid to water navigation.

The September 7 image shows New Orleans days after Hurricane Katrina struck. The flooded areas are dark, giving the city a bruised appearance. A straight vertical line separates a dark flooded area of the city from the light green-pink unflooded area. The floodwaters appeared to have stopped at the 17th Street Canal. This canal failed but the west dike held, keeping that part of the city from flooding.

Floodwater from the Gulf of Mexico made its way to Lake Pontchartrain, which then flooded this part of the city with an 11-foot storm surge. Water entered the canals but the canal walls did not overtop. The walls failed when water had only risen part of the way up the wall. When these canals broke, water from Lake Pontchartrain poured into these neighborhoods.

By September 7, the city had started to drain. Pumps worked to return the water to Lake Pontchartrain. About 380 cubic meters (100,000 gallons) of water were pumped out of the city every second.

Green vegetation has returned by the 2006 image, one year after the storm. Comparing the image from before Katrina and the most recent image, the amount of vegetation appears similar.

A temporary structure was quickly built over reactor number 4 to contain radioactive material. A more permanent solution was needed. About two decades in the making, a massive steel structure called the New Safe Confinement was built to seal in the site.

Segments of the structure were pre-assembled in Italy and shipped to Ukraine. To prevent exposure to radiation for the workers, the structure was erected 300 m away from the site. The framework was completed in 2014, and the entire structure was moved into place in November 2016. Notice the difference in its location between these 2015 and 2018 images from Sentinel-2.

Considered the world’s largest moveable structure, the new covering weighs 40,000 tons and is 843 feet across, 355 feet high, and 492 feet long. It’s tall enough for the Statue of Liberty to fit inside. At Sentinel’s 10-meter resolution, the huge structure appears as a bright set of pixels at the accident site.

The New Safe Confinement is expected to securely contain the radiation for 100 years.

These images show the dramatic urban growth within the Nile River Delta and the expansion of agriculture into adjoining desert areas. The Nile is the world's longest river at 4,160 miles. It flows south to north, bringing fresh, nutrient-rich water to Egypt.

In these images, red indicates vegetation. The contrast is clear between the lush vegetation of irrigated fields and the white or tan barren desert.

One solution to accommodate Copenhagen’s population growth is to grow inwardly as well as outwardly. Growth near the central part of the city will help encourage commuters to use mass transit and bicycles to commute to and from work.

Nordhavn is an artificial peninsula on the Øresund coast. Nordhavn is the northernmost extension off the coast of the central part of the city. Once a harbor for container traffic and cruise ships, Nordhavn is becoming a new trend in urban development. Development of the area began in 2011, and plans are to continue development for the next several decades.

This development is bringing the peninsula a new identity. It will become a mixture of housing, businesses, public spaces, parks, natural areas, and cafés. Dense urban development will minimize energy consumption used for transportation. People will find cycling, walking, and public transportation the easy and obvious choice.

The North Antelope Rochelle Complex is the most productive of the PRB mines. In 2018, the mine sold 98.4 million tons of coal. In 2017, it accounted for 13.1% of U.S. coal production. It began operations in 1983, and the series of Landsat images shows the progression of this mine since 1984.

While a large iceberg was threatening to form from the Halloween Crack or Chasm 1, a new rift suddenly appeared in satellite images in September 2019 just north of these features. The rift zippered across the ice at remarkable speed during the Antarctic summer of 2020–2021. The third major rift in this ice shelf to become active in the past decade, the North Rift lengthened by about 20 km between November 18 and December 22, 2020. It then grew an additional 8 kilometers by January 12, 2021.

Watch the new rift widen and flow westward with the ice shelf in the images. As you flip through, notice the McDonald Ice Rumples remaining stationary.

The rift continued to push northeast at up to 1 km per day as it cut through the 150-m thick ice shelf. GPS equipment detected a break on February 26, 2021. Landsat 8 got its first glimpse of the resulting iceberg, named A-74, on March 1.

In the northern portion of the delta, channels fill in between sand dunes during the flood season. Temporary lakes also fill during high floods. The water reaching these lakes is not returned to the river as flood waters recede.

The north receives far less precipitation than the southern portion. The mean annual precipitation there is just 200 mm (7.9 inches).

(Black stripes run through the 2011 image because of the Scan Line Corrector failure on Landsat 7 in May 2003.)

Not too long ago, Nouakchott, Mauritania, was a small fishing town. It became the country’s capital in 1958, shortly before Mauritania became independent. The town rapidly bloomed into a huge metropolis.

During a long series of drought years in the 1970s, thousands of rural families moved to Nouakchott in search of a better life. Refugees displaced by the Western Sahara War, which started in the mid-1970s, added to the city’s growth.

From small fishing town to rapidly expanding national capital, Nouakchott is surrounded by shifting sand dunes from the north and east, threatened by sea level rise from the west, and facing rising salty groundwater from below. Sand, salt, and water simultaneously threaten to damage the city from all sides. That’s why monitoring the region with Earth-observing satellites will be important for its future.

The PRB has become about more than just coal. Oil production is also increasing. Similar to the Bakken Formation in North Dakota, new technologies are allowing oil to be more economically recoverable.

Since 2009, hundreds of oil wells have been drilled in the PRB. In the second half of 2010, 219 drilling permits were received. In the first half of 2014, 1,161 permits were received.

These images show the region just west of the Black Thunder Mine. The 2014 image looks like a messy dot-to-dot drawing. The light dots, connected by crooked lines, are oil wells and the roads that lead to them.

In 1977, part of the Okomu Forest Reserve was given to the Federal Government for the Okomu Oil Palm Project. Between 1984 and 2011, the area of land used for oil palm plantations increased more than fourfold.

These plantations mostly appear in the northern part of the reserve. The image series also shows major changes in the southeastern part of the reserve, where the dark green is giving way to lighter green shades and pink. Small-scale subsistence farming is becoming more widespread. Logging and fuel wood collection also take place there under the forest canopy. People in this region can also sell forest products as a means of income.

These changes to the vegetation can cause increased localized erosion and flooding. Slightly higher than average rainfall can make the area vulnerable to flooding.

Closed-canopy tropical moist forest once covered large parts of this landscape near the Niger River Delta. Since the 1940s, however, logging, farming, and large-scale plantations have caused major losses of natural forest. In the middle of this increasingly degraded landscape, a fragment of relatively undisturbed rain forest remains.

In this series of Landsat images, plantations of oil palm and rubber trees appear in blocks of light green and magenta. Okomu National Park in Nigeria was designated in 1999 to protect a small population of forest elephants and several species of threatened primates within the Okomu Forest Reserve. Despite the large-scale rubber and oil palm plantation expansion in the northern half of the forest reserve and farmland in the southern half, Okomu National Park remains largely protected within the reserve and its dark green hue stands out against these surroundings.

This series shows the area around the famous Old Faithful geyser. Geysers and hot pools are the bright or blue spots within the dark green forest.

The vertical line on the left side of the images is the western park boundary. The patchy spots to the left of the line are logging areas outside the boundary. The 2011 image reveals another smaller burn scar just to the northwest of the airport at West Yellowstone, Montana, and the 2016 image shows another new burn scar at the top edge.

The fires scorched a lot of the park, but they did not destroy forests in one large swath. The severity of the burn varies. Unburned land is interspersed with the burned area. Dark red areas are severe burns, and lighter red areas are less severe.

Over time, the pink bare ground begins to give way to light green as vegetation returns.

The Mississippi River Delta has naturally meandered and migrated over time, building lobes of low swampland in what is now southern Louisiana. If left to its own, the river might migrate west and join the Atchafalaya to take a direct southerly route to the Gulf. However, a system of levees, flood gates, and canals prevents that from happening.

Built in 1963 to regulate the amount of flow into the Atchafalaya, the Old River Control Structure prevents the Atchafalaya River from capturing the Mississippi. The system keeps 70% of the water in the Mississippi.

The 2022 image labels the parts of the Old River Control Structure and rivers. With more than 50 yeas of data, the Landsat program is a valuable tool in continuing to monitor both the land loss and land gain of the Mississippi River Delta.

In these images, bright green indicates aquatic vegetation on the Omo River delta. The size of the delta changes over time in these scenes because of changes to the lake’s water level. The delta expands and shrinks in response to the high rainfall variability in the region. However, if a significant amount of water is diverted from the Omo River for irrigation, the natural dynamics of the lake levels could be affected.

In the 2011 and 2015 images, curious features appear: green swirling shapes south of the delta. We know that green indicates growing vegetation in these images, but is this shallow water being exposed with more aquatic vegetation taking hold, or is this vegetation floating on the water’s surface? Examining the lake’s depth reveals that it is too deep in this area to be growing, rooted plants. So it must be vegetation or weeds floating on the surface.

The maximum depth of this large lake is only 40 feet. The entire surface freezes all the way across each winter, with ice reaching 2–4 feet thick.

That’s thick enough to drive cars and pickups on. According to the Minnesota Department of Natural Resources, clear ice 16 inches thick can support a heavy-duty pickup.

Some years look a little busier. In some images, the lake looks smudgy with snow or wind. So the view depends on local conditions on the day of Landsat overpass.

An artificial island first appears in the Øresund Strait in the 1998 image. The 4-km-long (2.5-mile-long) island is called Peberholm and was built from material dredged from the seabed. It’s a key point in the construction of the Øresund Link, which connects Copenhagen and Malmö.

Open for traffic since 2000, the Øresund Link is made up of three segments. Starting from Copenhagen on the northern end of the airport, the link begins with an underwater tunnel that is 3,510 meters (2.2 miles) long. The roadway on Peberholm Island is 4,055 meters (2.5 miles) long. Finally, Øresund Bridge spans the rest of the strait to Malmö. The cable-stayed bridge is 7,845 meters (4.9 miles) long and is visible as the thin line curving from the island to Malmö.

The physical growth of Orlando, Florida, especially to the east and south, is apparent in these images. Builders in the area have to plan construction carefully because this land is karstic. Karst terrain is characterized by springs, caves, sinkholes, and a unique hydrogeology that results in aquifers that are highly productive but extremely vulnerable to contamination.

The term karstic comes from Karst, a region in the Balkans whose underlying rock is limestone, which slowly dissolves in the groundwater giving it a distinctive terrain and water cycle. Karstic lands comprise 5 to 10 percent of the Earth's land surface, where oceans have retreated as they did in Florida. Millions of years ago, Florida was under water; calcium crystals and seashells sank to this ocean floor and gradually compacted into hard limestone. As the ocean dropped, Florida became covered by plants and soil, and subject to rainwater.

Selkirk Island is not the only place where Landsat has seen vortex streets. Other places where this phenomenon is common are nearby Robinson Crusoe Island; the Kuril Islands, Russia; Guadalupe Island, off the western coast of Mexico; and the Aleutian Islands, Alaska. The reason for the cloud patterns is the same: tall, steep-sided islands that affect the motion of passing clouds. That first image over Selkirk Island in September 1999, however, is still the clearest vortex street Landsat has recorded.

The current spongy moth outbreak is thought to be the result of a series of unusually dry springs in 2014, 2015, and 2016, which suppressed a fungus that keeps the moth population in check. The fungus (known as Entomophaga maimaiga in the scientific world) infects the caterpillars and causes high rates of mortality. However, researchers believe that during this outbreak, low precipitation during key periods in the spongy moth life cycle resulted in lower amounts of this fungus, so the fungus was not as effective and the moth population was not kept in check.

A healthy tree can survive a defoliation by the caterpillars. It can usually produce new leaves in the same growing season. However, consecutive years of caterpillar attacks can cause tree mortality.

The more a river meanders, the more cutoffs form. Cutoffs form more frequently on rivers that have more sediment. Flanking the Mamoré River in these images are numerous oxbow lakes, formed from these cutoffs.

An oxbow lake starts as a meander, or curve, in the river. Sediment builds up on one side of the curve, called deposition. The river becomes more curvy until the river ultimately loops back onto itself. The river then flows along the straighter path and forms a cutoff. Once the river completes this shortcut, the curve becomes a separate body of water, called an oxbow lake.

Over time, the oxbow lake fills with sediment and detritus and eventually becomes a swamp or bog for a while and then often dries up as the water evaporates.

A new drilling technique called pad drilling reduces the overall footprint of land cover change caused by the industry. Several horizontal well bores are drilled from a single larger pad. Pad drilling became more widespread in 2010 and now accounts for about 75% of all new wells. While the number of wells drilled can increase, the land requirement for increased production is not as extensive. Furthermore, other infrastructure, such as roads and pipelines, are reduced overall.

Pad drilling also has the benefit of more wells being drilled in less time. A significant area of underground resources can be tapped with minimal impact on the surface. Even as the number of new drilling wells slows, production can continue to increase.

On June 27, 2014, new fissures erupted just east of Pu‘u ‘Ō‘ō crater and lava advanced rapidly to the east. By late October, lava had advanced 20 km toward Pāhoa. The flow eventually stalled 1,800 feet (550 m) from the Pahoa police and fire stations. It also reached within 500 feet (150 m) of Pāhoa’s main street before stopping. By mid-December, the lava flow threatened the Pāhoa Marketplace shopping center but no damage was done there. The entire flow extended 13.5 miles (21.7 km).

Landsat imagery shows this flow as ragged, dark lines protruding from the main lava flows around Pu‘u ‘Ō‘ō. An image from the European Space Agency’s Sentinel-2 satellite shows the lava flow and Pāhoa in slightly higher resolution and makes it clear just how closely the flow approached the community.

Palm Jebel Ali is another island similarly shaped to the Palm Jumeirah and slightly larger. And like Palm Jumeirah, this artificial island was built quickly in the early years of the 2000s.

After the financial crisis of 2008, development slowed down. In fact, construction on Palm Jebel Ali was suspended in 2009, and relatively less change is visible between the 2008 and the 2022 images.

Planning is again underway to develop the island but at a slower pace. Similar to Palm Jumeirah, Palm Jebel Ali will include apartments, homes, offices, and hotels.

Palm Jumeirah was the first of the artificial islands off the coast of Dubai to be built. Shaped like a huge palm tree, it added 56 kilometers (35 miles) to Dubai’s coastline.

Palm Jumeirah includes a trunk with 17 fronds surrounded by a crescent-shaped breakwater. Residences are on the fronds, the trunk has apartments, and hotels line the crescent. The crescent also has a large water park called Aquaventure.

In the early years of the 21st century, substantial progress is seen on this artificial island. Once the island takes shape, vegetation is seen increasing on the new land. The progress on the island matched the urban growth inland during the same time period. New roads, expanded urban areas, and increased vegetation mark the most visible changes in these images.

Understandably, many countries are pursuing renewable resources to get away from the reliance on fossil fuels. However, new research has determined that palm oil doesn’t reduce greenhouse gas emissions at all—producing biofuel from palm oil may actually increase greenhouse gases as much as burning fossil fuels does.

One of the reasons is peat land. Much of the rain forest that is being converted to palm oil plantations is located on peat land. These natural carbon sinks sequester huge amounts of carbon. Cutting these forests and draining the peat land releases this stored carbon that has been there for thousands of years. Besides that, the carbon costs in fertilizing and managing the crops, processing the products, and transporting them outweigh any benefits.

Forest cover in West Papua was estimated to be 33 million hectares in 1997. That reduced to 30.4 million hectares by 2004. Even more plantations appear in the later images.

The growth of the palm oil industry has transformed part of the tropical rain forest of Papua, Indonesia, into gridded blocks of palm oil plantations. Indonesia produces a little over half of the world’s palm oil. Together, Indonesia and Malaysia produce 87% of the world’s palm oil.

Palm oil is used in about half of all consumer goods. It is found in cooking oil, soap, food additives, and myriad other products. You have almost certainly used palm oil recently probably without knowing it.

The Pasig-Potrero River drains the east side of Mount Pinatubo, just south of Clark Air Force Base. Following the 1991 eruption, pyroclastic flows buried about one-third of the Pasig-Potrero watershed.

A series of lahars that occurred in the years after the eruption made the Pasig-Potrero channel wider. After the eruption image from July 1991 (really just a brown and gray mess under a few puffy clouds), a bright purple-pink lahar appears downstream on the Pasig-Potrero River. The sediments are redistributed over time, until the October 1994 image shows a larger change to the river. A lahar alongside a previous one more than doubled the area covered by sediment. The 1996 image shows more clearly even further lahar action with bright pink hues. Recent images show the reestablishment of farm fields, though the land and river course are altered from what they were before the 1991 eruption.

The 1996 image indicates the beginning of dike construction. These dikes, along with a reinforced dam built along the southern slopes, create a sediment retention area. The dikes stand 5 to 15 meters tall.

These images also hint at the lingering hazard in this region. A growing population is indicated by the urban growth of the city of Angeles in the upper center of the images. This city, with a 2016 population of about 900,000, is near Clark Air Force Base; the long straight lines are the runways of the air base. Clark Air Force Base closed soon after the Pinatubo eruption. However, it reopened to U.S. forces in June 2012, when it was called Clark Air Base. A new highway was also completed by 2007, seen in the image winding past the air base and to the lower left.

In early 2017, clouds covered the Pasig-Potrero River area in all available Landsat images. The image ASTER captured on February 23, however, was clear. With many cloudy days in this part of the world, these sensors complement each other, filling in when the other sensor detects mostly clouds.

Even more than two and a half decades after the eruption, lahar hazards may continue. Landsat and ASTER help monitor changes caused by these hazards and how the changes to the land affect the population.

In 1978, the Pearl River Delta (PRD) region in southern China had a population of just under 10 million. The population was scattered between several medium-sized cities on an interlacing network of rivers and streams.

Some of those cites have become megacities, and the entire region has merged into one continuous, if scattered, megalopolis with a combined population greater than the six U.S. New England states plus New York, New Jersey, and Pennsylvania.

The PRD now has a population higher than Tokyo, making it the world’s largest urban area.

In 1978, China began new economic policies that loosened regulation for migrating within the country, and people either moved permanently to cities to find work in industry or moved there temporarily for seasonal work. In-migration has been the largest contributor to the rapid population rise. The new model also opened up the country to foreign investment and less government control on private businesses.

Landsat’s long record and spatial resolution make it ideal for mapping change in areas that are urbanizing rapidly, such as the Pearl River Delta. Urban area growth dominates the later images in this Landsat time series.

Municipalities and Special Administrative Regions of the Pearl River Delta

2022 estimated population

* For comparison, the population of Tokyo is 37,732,000

The Pearl-Qatar is 32 kilometers of new coastline extending into the Persian Gulf. It is so named because Doha began as a pearl fishing village in the 1800s. The Pearl-Qatar is built on one of the country’s historical pearl diving sites.

Construction of the Pearl-Qatar began in 2004. Once completed, it will contain over 19,000 residences that will include townhouses, luxury apartments, beachfront homes, luxury hotels, shopping, fine dining, marinas, and entertainment.

The string of nine artificial islands to the east is called Isola Dana. These private islands each have a personal beach and protected harbor for yachts.

These close-ups show another core zone area of the reserve called Pelon. Forest disturbance is most visible in the 2000 image. Later Landsat images reveal some red filling in in this area. In the Landsat imagery, red indicates any actively growing vegetation, so it may not be the tall trees of oyamel forest recovering yet. The Global Forest Change data do reveal some blue pixels in the Pelon site, so there is potentially some recent recovery occurring.

The northern side of this site had been stripped of several historical colony sites by the time of the 2000 Landsat image. The Global Forest Change data don’t show some of this area as forest loss because that study uses Landsat data from 2000 to 2013, so the areas that are black were already non-forest by 2000.

A feature west of Sydney changes shape and color throughout these four images, indicating constant change in that location. This area, which covers about 1,935 hectares, is the Penrith Lakes mining and reclamation project.

Located on the floodplain of the Nepean River, Penrith Lakes is the largest sand and gravel quarry in Australia. Eventually, quarrying activities will end and the entire site will be completely turned into parkland and lakes. Three main recreation lakes are planned, and the northern lake will be a wildlife sanctuary. During the first stage of the reclamation, the southern part of the area was turned into the kayaking and rowing venue for the 2000 Summer Olympic Games.

Petermann Glacier made headline news in 2010 and again in 2012 when large pieces broke off the end of the glacier and floated out to sea. Located on the northwestern coast of Greenland, Petermann Glacier covers 1,295 square kilometers. Its floating ice tongue is 15–20 kilometers wide and 70 kilometers long—the longest floating glacier in the Northern Hemisphere.

A glacier is made up of fallen snow that has been compressed into a large thickened ice mass over many thousands of years. Tidewater glaciers flow like very slow rivers to the ocean, and at the boundary between the glacier and the sea, ice breaks, or calves, from the end, creating icebergs.

This calving is normal, but it’s worth watching Petermann and other Greenland glaciers closely. Petermann is one of the major marine-terminating glaciers of Greenland. Ice loss from the Greenland Ice Sheet has increased recently. An article in Nature concluded that climate change may cause Petermann and other Greenland glaciers to contribute to sea level rise. Landsat helps glaciologists keep a close eye on this remote but significant glacier.

From 1975 to 1978, Cambodia was ruled by the Khmer Rouge regime, which sought among other things to build a vast system of irrigation canals. These images show an area around Cambodia's capital city of Phnom Penh where such waterworks were built. Many areas east of the Mekong River show a gridwork of canals by 1985.

Phoenix, Arizona, and its suburbs are growing rapidly, both in population and area. Landsat images show striking changes in the Phoenix metropolitan area in only a few decades. The most noticeable change is residential areas spreading over agricultural fields, which are shown in the images as bright red squares and rectangles. But in other areas, the urban growth expands over what was once bare desert.

New residents and tourists are attracted to Phoenix by the warm weather and abundant sunshine. Phoenix has maintained rapid and sustained growth, and its location in a wide valley allows neighborhoods to be built with houses that can have a lot of space around them. From 1970 to 2023, the population of the Phoenix metropolitan area grew by 422 percent.

Phoenix doesn’t have many cloudy days, so it’s perfect for studying urban growth with satellite images. Scientists and city planners study population growth and urban expansion in fast-growing cities like Phoenix to determine the changes that have occurred over time and to see how those changes impact the surrounding environment, affect the availability of natural resources such as water, and alter the landscape and how it’s used. That information can help people plan for future changes as cities continue to grow.

Population Growth of Greater Phoenix

The central phosphate region of Florida has been strip mined since 1888. By the 1980s, it accounted for almost 30% of worldwide production, and almost three quarters of U.S. production. 93% of Tampa Bay's exports are phosphates. Almost all mined phosphate goes into crop fertilizer. Modern phosphate mining involves complete removal of the land—plants, animals, soil, water, even bedrock—and then its approximate reconstruction minus the phosphate.

The steps are as follows:

• The area to be mined is first stripped of vegetation and the water table is lowered, typically by digging a deep trench around the area.
• An enormous crane-like machine, dragging a giant bucket, strips away the 20–50 feet of soil and stacks it nearby in an already-mined area. Then the dragline scoops the exposed phosphate ore, mixed with sand and clay, into a pit.
• The ore in the pit is blasted by high-pressure water jets into a milkshake-like slurry.
• This slurry is pumped by pipeline to a processing plant that separates the sand, clay, and phosphate ore. The phosphate ore is shipped to another plant that processes it into fertilizer.

This process creates several byproducts besides fertilizer. Topsoil lies stacked by the mine. Sand has been separated from the phosphate ore and pumped back from the processing plant to the mine where it is used to restore the site when mining is complete. Fine-grained clay has also been separated and is more troublesome since it stays mixed with the slurry water and swells to three times its original size. Finally, every pound of manufactured fertilizer also creates five pounds of phosphogypsum waste.

Since 1975, state law has required mining companies to reassemble these byproducts back into a reclaimed semblance of the pre-mined landscape. This means bulldozing the piles of topsoil and sand into gentle slopes and replanting them with vegetation sufficient to hold a 25-year downpour as well as the pre-mined land could. Sometimes part of the clay is mixed with this bulldozed sand, but most clay gets pumped into settlement ponds, where over several decades it consolidates to an acceptable density, though still more swollen than before mining. Many of the water bodies visible in the Landsat images are settlement ponds. These aboveground ponds are contained by earthen walls that have occasionally burst, releasing billions of gallons of waste water, threatening water quality and human lives.

A more stubborn problem is the phosphogypsum. This byproduct of fertilizer manufacture is too low-grade to be used like mined gypsum in products such as wallboard. It is also acidic and contains low levels of carcinogens like radon. It is kept out of reclamation and piled in massive "gypsum stacks" up to 200 feet high. Possible uses for the phosphogypsum such as roadbuilding have been stymied by toxicity concerns. Even establishing plant cover on the stacks has been challenging.

Meanwhile, the stacks grow rapidly. Recent regulations require liners under new stacks, but in 1994 an existing stack of 80 million tons was struck by that old karstic hazard, a sinkhole. Fifteen stories deep, it dumped millions of cubic feet of water and gypsum into the aquifer.

You can see in these images the expansion of the mined area, its southward shift, and the progress of individual mines through the mining process. Look for this progression: lush vegetation (red), then perhaps bare earth (bright), then ponds (black if deep and clear, brighter blue if shallow and/or full of sediment), and finally reclaimed vegetation (red if lush, pink if not).

Engineers use test sites around the world to make sure Landsat imagery is consistent and accurate. These calibration test sites are regions on the Earth that remain stable over long periods of time. They do not change year to year or season to season. They are typically deserts or dry lakebeds with very low humidity, low atmospheric changes, and little to no human intervention.

These sites are described as pseudo-invariant. They are not completely invariant because no site can be perfectly stable over time and varies to some degree. So engineers refer to the sites as Pseudo-Invariant Calibration Sites, or PICS.

The idea of studying these test sites is simple. Engineers look at a spot of land that is expected to remain consistent. The reflectance at different wavelengths of light in the Landsat data should stay stable. When changes occur in these reflectance values, it may mean the sensor’s response has shifted.

Examples of other test sites are the remote desert sands of Libya, the Railroad Valley Playa lakebed in Nevada, and even the straight bridge that crosses Lake Pontchartrain, Louisiana. (The span of the bridge happens to be nearly aligned with the Landsat ground track.)

Air temperature increases can bring about long-term loss of ice mass from a tidewater glacier. An increase of less than 2 degrees Celsius over the mean annual air temperature is all it takes to trigger glacial retreat. In fact, Alaska has seen an increase in mean annual air temperature of 1.7 degrees Celsius over the past 60 years. But once a glacier has begun retreating, temperature alone does not have as much influence on its behavior. The topography of the valley the glacier is in affects it much more.

For example, the pace of Columbia’s retreat has been uneven. Its retreat slowed between 2000 and 2006 because it reached a narrow spot in its valley. This spot between Great Nunatak Peak and Kadin Peak constricted the glacier’s movement. Known as a pinning point, this topographic constriction is a place where the glacier’s trough becomes either too narrow or too shallow to continue moving at the previous rate. A pinning point can be a location of enhanced stability for the glacier.

If a glacier retreats from a pinning point, it will retreat until it reaches another pinning point upstream. A glacier that remains at a pinning point for a longer time may build another moraine.

Calving is also affected by the topography of the glacier’s valley, and calving rates increase in deeper water. Researchers found that as Columbia continues to retreat, it will reach water that is shallow enough to provide a stable position within a few years and remain stable through 2100. In this shallower water, iceberg production will be slowed.

At the western end of the Mesabi Range is another consequence of the mining industry. Once mining operations halted in some parts of the Range, the deep open pits that were created were left to fill with rainwater and groundwater inflow. One of these lakes is the Canisteo pit lake.

At about 4.8 miles long and 0.5 mile wide, it’s about the same size as Trout Lake to the south, a natural lake. The Canisteo pit is actually a complex of 19 inactive mine pits. The lake is now an average of 100 feet deep, with its deepest point a remarkable 300 feet. (For comparison, the deepest point in Mille Lacs Lake, Minnesota’s second largest lake, is about 40 feet.)

The filling of this pit lake concerns residents of the adjacent small towns. Without some kind of intervention, these towns could eventually flood. The current temporary solution is a drain tile system to carry groundwater leaving the pit toward Trout Lake.

The Hill Annex Mine pit lake is also in this scene, just east of Canisteo pit lake. This lake is also very deep. Hill Annex Mine State Park is located on the lake’s shores.

The USGS aerial image shows the open pit mines that are now Canisteo pit lake. The towns of Coleraine and Bovey sit between these mines and Trout Lake.

Production in the Escondida Mine in Chile’s northern Atacama Desert began in 1990. Total mined copper production through 2014 was 22 million tons, 21% of all copper mined in Chile.

It’s easy in these Landsat images to see the extent to which the open-pit mining operation is expanding. But it’s harder to appreciate how deep the pits are. The main pit at Escondida is 645 meters deep. If you could stack two Eiffel Towers inside the pit, the top one would just barely peek over the edge.

Wyperfeld National Park now covers 360,000 hectares, with its western half an official wilderness. The park is habitat for black-faced mallee kangaroo, desert hopping mice, 50 species of lizards and snakes, and 250 species of birds including parrots and eagles. Mallee fowl, a rare mound-nesting species almost extinct by the 1950s, also live in Wyperfeld’s vast shrubland.

Much of the park’s vegetation is mallee, a type of shrubland dominated by several sparse, tall varieties of eucalyptus. These eucalyptus have large underground tubers which sprout several stems after a fire, giving the mallee its distinctive look. The vegetation ranges in structure from short heath to tall, open woodlands but is commonly a thick, impenetrable scrub forest. Areas along the river are dominated by river red gum trees, which grow in the wetter soil there, and by black box trees, which grow in the slightly drier soil. These trees act as a natural record of floods, since they germinate in wet soil. The park also has stone-forming fungi, whose rootlike feeding-threads cement the sandy soil particles into underground “stones” of up to 20 pounds. These stones incorporate black rings of ash, forming a natural archive of fires.

The Mamoré River carries sediment from the rapidly eroding Bolivian Andes. The steep terrain coupled with high river discharge in the Andes causes a high degree of soil erosion.

The high sediment load encourages the growth of point bars, which are seen in these Landsat images as the lighter colored areas along the inside bends of the river. These sandy areas are mostly vegetation-free. Point bars increase the erosion on the opposite side of the river, causing it to further push the river’s course off to the side.

These close-up images show a location on the Mamoré River where several point bars have formed. At the top of these images, this action created a cutoff. Point bars tend to increase the rate of cutoff formation. And the bends that have more sediment (pink) move more than the bends that have less.

View this animation to really see this process in action.

Salar de Atacama in northern Chile is a salt flat and major source of lithium. While some dry lakebeds have occasional inundations that partially dissolve the surface crusts, the center of Salar de Atacama is continually dry, so its surface is rough.

Landsat images show an increasing number of evaporation ponds sprawling across the salt flat. Large amounts of lithium-rich brine are pumped to the surface from up to 30 meters below the saline crust. Canals bring the brine to ponds for efficient evaporation in this dry, windy place. Potassium chloride, potassium sulphate, boric acid, magnesium chloride, and lithium chloride are left behind. The lithium chloride is treated with sodium carbonate to produce lithium carbonate, the primary ingredient in lithium-ion batteries.

The lithium concentration in the Salar de Atacama is the highest in the world. That, along with the fast evaporation rate, means the region has the planet’s largest deposit of economically recoverable lithium. Salar de Atacama has an estimated lithium content of 6.3 million tons.

Phnom Penh is the largest city along the Mekong River. Its population fluctuated wildly during the 1970s and 1980s; the population of 1.2 million in 1971 swelled with war refugees to 2 million or more by 1975, when it was evacuated to almost nothing by the victorious Khmer Rouge communists. From 1978 (the last year of the Khmer Rouge regime) to 1987, Phnom Penh's population is estimated to have grown from about 50,000 to 700,000 people. The 2022 population was over 2.4 million.

A note on terms: Phnom Penh is pronounced p-NOM PEN. Phnom means "hill" or "mountain" in Khmer; Penh is a woman's name. More than 90% of Cambodians are ethnic Khmer, and Khmer is the national language. Cambodia has also been known as Kampuchea.

About 76 million people live within 500 kilometers (310 miles) of Lake Urmia. Residents of the region fear that what has happened to the Aral Sea is happening to Lake Urmia. The almost complete loss of the Aral Sea has had serious economic and environmental consequences. The population near Lake Urmia is denser, so more people are at risk.

The city of Urmia is the gray patch in the lower left of these images. Agricultural fields spread out to the north and east of the city. The oval shape on the east side of the lake is an extinct volcano. This feature was an island as recently as 1998. A causeway and bridge completed in 2008 connects the oval and the western shore. Construction of the causeway began in 1979, was abandoned, and then started again in the early 2000s.

Every day, 100 empty trains enter Wyoming. They leave fully loaded with coal. The United States has the largest coal reserves in the world, and much of it lies in the Powder River Basin (PRB) in Wyoming and Montana. The PRB, which lies between the Black Hills in South Dakota and the Bighorn Mountains in Wyoming, produced 43% of the nation’s coal in 2019.

According to a study by the U.S. Geological Survey, the PRB contains 25 billion tons of economically recoverable coal. This does not mean it’s all mineable. The amount of economically recoverable coal can change based on mining costs and coal prices, which change based on market conditions. Nevertheless, the region has a lot of coal that is very accessible.

The Black Thunder Mine and the North Antelope Rochelle Complex are two of the largest open-pit mines in the PRB. They lie within the Thunder Basin National Grassland. These mines have been expanding over the past few decades, and the land change is evident in this time series of Landsat images.

The main purpose of the GERD is power generation, and its 13 turbines are expected to produce about 16,000 GWh of electricity annually. That will double Ethiopia’s previous output of electricity and provide power to 60% of the country’s population.

Recent years have provided ample rainfall in the region to fill the reservoir. But what happens during a severe drought?

Even a gradual filling of the reservoir may lead to a reduction in water supply downstream, potentially affecting hydropower generation and irrigation. However, water stored in the GERD reservoir can mitigate the impacts of drought once it’s fully operational. Such water releases also generate more power.

Besides power generation, the GERD will help regulate seasonal flooding, preventing destructive floods during heavy rains. And the reservoir will provide a steady supply of irrigation water for the downstream countries of Sudan and Egypt.

Finding the right balance between power generation and water use downstream is the main challenge for the countries that rely on the Nile River system.

Rectangular shapes cover the Salar de Atacama in northern Chile, a major source of lithium. Landsat images show evaporation ponds expanding over time.

Lithium-rich brine, which at first looks like dirty slush, is pumped to the surface and sent via canals to these evaporation ponds. The dry, windy climate makes for efficient evaporation and leaves behind concentrated salts, from which lithium can be extracted.

The ponds, which are about 10 feet deep, vary in color in the images because of varying amounts of salts in the water. The brighter ponds contain more concentrated salts. The deep blue ponds indicate more water content.

The lithium is reduced to a concentrate and then shipped by tanker truck to a refinery on the coast in Salar del Carmen. From there, it’s on to the rechargeable battery you depend on to power your smartphone.

The 2018 eruption was part of an ongoing eruption sequence that started on January 3, 1983, with fissures breaking out along the East Rift Zone.

Over the next 3 years, constant fountaining from one vent built a cone named Pu‘u ‘Ō‘ō. Eruptive activity continued from this vent until 2018, the longest East Rift Zone eruption ever recorded.

Landsat images show the area around Pu‘u ‘Ō‘ō. The 2018 lava flow emerged farther along the East Rift Zone to the northeast.

As part of the Toshka Project, a pumping station sends water from Lake Nasser to irrigated fields in the Toshka basin. The Mubarak Pumping Station has a discharge capacity of 1.2 million cubic meters per hour through the Sheikh Zayed Canal.

The pump house is like an island. Its 24 vertical pumps are arranged in two parallel lines. The intake channel is 50 meters deep, the deepest inland channel ever built. This innovative engineering marvel is even earthquake-proof.

About 138 kilometers of canals carry the Nile water from the pumping station in Lake Nasser to irrigated fields west of the reservoir. By the 2013 image, the Sheikh Zayed Canal makes a clearly visible line to the northwest from the bay where the pumping station sits.

A fast-growing city in India is a study area for urban impervious surface and the urban heat island effect. Located in western India about 120 kilometers southeast of the coastal city Mumbai, Pune is known as an educational and industrial center. Its population has grown from 450,000 in 1950 to nearly 8 million in 2021. People from rural areas are migrating to the city for better employment opportunities. The education and industrial sectors are also attracting people to Pune from other countries.

False-color Landsat images show the steady expansion of the Pune metropolitan area. Forests cover higher elevation land, shown in bright green mostly to the west. Dull colors are shrubland and grassland, which occupy the lower elevations. However, urban land—the lavender and purple hues—has been expanding over grasslands, barren, and agricultural land.

Pune’s proximity to Mumbai is also leading to its growth. The Mumbai–Pune expressway has reduced travel time between the two cities, so Pune has become a destination for those looking for housing away from Mumbai.

West of Pune is the Western Ghats mountain range, a relatively low range of forested mountains. One of the peaks west of Pune reaches just over 1,220 meters (4,000 feet) of elevation. Rivers flow out of the mountain range toward the east—reservoirs along the rivers store water for the populations downstream. The Mula River and the Mutha River meet in Pune to form the Mula-Mutha River as it flows toward the east.

In such a large city as Pune where the population is growing and those built-up surfaces are expanding so rapidly, the associated effects of streamflow changes and the urban heat island effect need to be measured and monitored.

Glaciers move slowly, but Bear Glacier seems to have racing stripes. Glaciers pick up dirt and debris from the rocks they pass. They deposit that material in accumulations called moraines. A lateral moraine is the material on the sides of a glacier.

Two glaciers flowing together form a medial moraine in the middle where they join and show up as those dark stripes. When a glacier has a medial moraine, it’s made up of more than one ice flow.

Randolph Air Force Base is visible as two white strips northeast of the city. The base’s streets were laid out in a series of concentric circles, with the runways along the east and west sides. This pattern can be seen in the series of Landsat images. Randolph Field was dedicated on June 20, 1930, so there is not much change to see to the base itself. What changes is the amount of residential buildup surrounding the base, development creeping in from the southwest and spilling over the north side of the base.

Street patterns in residential areas are clearer in some images than in others. As trees in these neighborhoods mature, they begin to cover the streets, so you will see this progression in these images.

Over the last few decades, Dallas’ urban/suburban areas have expanded rapidly by consuming arable land in the countryside. The city is expanding in almost every direction. These images show the northeastern suburbs of Plano, Allen, and McKinney. The lake on the east side of the images is Lavon Lake.

April 19, 2009, could have been a rare clear view of the island, but some of the data are missing because of Landsat 7’s Scan Line Corrector (SLC) malfunction of May 2003. Landsat 8, which launched in February 2013, has been more fortunate in its relatively short time in orbit to capture at least three clear views of the island: on March 8, 2014, March 11, 2015, and January 11, 2017. Those three images look about the same except for subtle changes to the mountain shadows caused by a different sun angle at different times of year.

The Dead Sea is fed mainly by the Jordan River, which enters from the north. Because of irrigation projects and other water needs upstream, the level of the Dead Sea has been falling.

Much less water now enters the sea from the Jordan River. The river once brought 1.3 billion cubic meters of fresh water every year into the sea. Now it brings only about 100 million cubic meters, most of it containing agricultural runoff and sewage. These water uses have a bigger impact on Dead Sea levels than rainfall, which only amounts to an average of about 50 millimeters annually.

Over the past 50 years, the level of the Dead Sea has dropped by 45 meters, and the rate of decline is increasing. From 1930 to 1973, the sea declined 17 centimeters per year. From 1974 to 1979, it dropped 62 centimeters per year, and from 1981 to 1990, 79 centimeters per year. From 1994 to 2001, the sea declined 100 centimeters per year. A 2018 report by Israel’s Ministry of Environmental Protection notes a rate of decline of 1.2 meters per year.

As the water level continues to drop, the water only gets saltier. There is even a layer of salt coating the lake bottom, which has been growing about 10 centimeters thicker every year.

To make matters worse, as the water retreats, sinkholes form in the salty seabed that is left behind. Studies have inventoried the sinkholes along the coast of the Dead Sea and found that the sinkholes are increasing in number, making development on this land hazardous.

Roughly 138,000 images were taken by the RBV on Landsat 3. The data were recorded to 70-mm black and white film rolls at the NASA Goddard Space Flight Center and delivered to EROS. This film, stored either on 70-mm film or in envelopes on film “chips,” is part of the EROS archive, and it’s the only copy.

Only 64 of those images have been scanned from their film source for immediate download via EarthExplorer (look under Landsat Legacy in the Data Sets tab). The rest of them are there and you can find their locations, but the film would have to be scanned before you can download a high-resolution version.

If a scene has not been already scanned, users can place an order to scan the film for $30 per scene. Once it’s scanned and a high-resolution digital version made available for download, it’s freely available worldwide. But as noted, any of these images have a decent chance of having geometric distortions.

Landsat’s RBV had an inauspicious beginning. It rode into orbit on Landsat 1 on July 23, 1972. During orbit 196, just 14 days later, a relay in the Power Switching Module of the spacecraft got stuck in a permanently “on” state.

The problem could have been fixed with a difficult command sequence, but the other sensor on Landsat 1, the MSS, was already showing its excellent performance and became the favored sensor for its capability to acquire near-infrared data. So the RBV on Landsat 1 was not reactivated. In the short time it operated, it recorded 1,692 images.

The RBV camera that flew on board Landsat 3 was redesigned and given a slightly different mission. This RBV had a spatial resolution higher than the MSS, 40 meters, to add a new dimension to the MSS’s multispectral coverage. The higher detail could be used for detailed ground mapping. The Landsat 3 RBV acquired many thousands more images than either one on board Landsats 1 and 2. The RBV imagery is scattered across the globe, and all of it resides in the EROS archive.

Because of RBV’s higher spatial resolution than MSS, glaciologists were able to use the RBV imagery for spotting more detail. “If you want to look at the ice front, you want to get as sharp a picture as you can,” John Dwyer, Chief of the EROS Science and Applications Branch, said. “They could map crevasses and their displacement and movement over time and map the surface velocity. Once you straighten out the geometry of the image, the RBV can still be useful.”

Yes, the geometry of an RBV image had to be “straightened out.” It turns out there are a few problems inherent in the RBV data.

The RBV was more like a television camera than a sensor, but television pictures tended to distort the image. Researchers using satellite imagery want the image to resemble an accurate map. They expect straight lines for latitude and longitude, for example. RBV images, however, were more like maps printed on a rubber sheet. They were easily stretched out of shape, distorting those imaginary latitude and longitude lines. These distortions could be corrected, but that would have increased processing time and cost.

Furthermore, when imaging over Antarctica, RBV tended to go snow blind. Areas of high reflectance, like snow and ice, could be overexposed. Therefore, cloud cover and snow cover were easily confused.

Because RBV’s main purpose was mapping the earth, the imagery included a reseau grid. No other Landsat sensors contain reseau marks. These plus signs on the images are used to correct distortions in the image after development or scanning. As John Faundeen, Archivist at EROS, put it, the reseau marks allowed you to “tie the imagery to the earth to verify the accuracy.”

In all, there were officially 11 inherent problems with RBV data. Other problems include corners out of focus, occasional black vertical lines, and missing or distorted reseaus. These problems are detailed in a 1981 USGS Open-File Report.

The RBV image shown in this section is in Brazil and shows a stairstep anomaly on the right side of the image. This stairstep phenomenon appears in several RBV images.

Nouakchott is surrounded by a succession of sand dune belts, some of which are highly mobile and can reach 20 m high.

North and east of the city, a green belt was established between 1975 and 1990. Various trees and grasses were planted to curb sand encroachment. Evidence of this effort is seen in Landsat images, where the green belt actually appears red. Landsat’s ability to see various infrared wavelengths of light allows us to more easily differentiate actively growing vegetation from the urban areas and open desert. This vegetation appears red in these images because of Landsat’s near-infrared imaging capability, which reveals actively growing vegetation.

This green belt has changed recently because of the city’s expansion. From 2000–2007, a new project extended the plantings around the city. During this project, 800 ha of inland dunes were stabilized with various trees and grasses.

A closer look at the site of the power plant in the 1986 image shows a red spot near the location of reactor number 4. The high brightness of those pixels indicates a high temperature heat source. This heat source and darkened strip that extends to the west indicate an explosion, with the reactor still emitting high heat three days later.

Since their start in the 1950s, the mines have moved, following the coal deposits. In the zoomed-in 1973 image, the mines appear in the northern part of the image. In the rest of the sequence of images, the mines shift and change shape, generally moving south.

Federal law requires the restoration of mined lands to their approximate original contours. It also requires that reclaimed land support either the same or better land uses than it supported before mining. To meet this requirement the Muskingum mines, as well as other mines, are replanted to grassland, for agricultural use. The mining company replaces the topsoil, grades the soil, and applies grass seed and mulch.

The mining company also planted some of this land to forest. As part of the voluntary Climate Challenge Program, the American Electric Power Company planted millions of trees on company-owned grassland. These new forests decrease the carbon dioxide in the atmosphere, control erosion, and provide habitat for wildlife.

In the Landsat images, much of the reclaimed land is distinguishable from the surrounding forest. Generally, bright pink is new mined land. As land is reclaimed, it turns darker and then becomes green as the vegetation returns.

The Surface Mining Control and Reclamation Act of 1977 requires that mined lands be restored to an acceptable land cover. These images show some of the landscape returning to green after mining operations have moved on. But the contours of the land are not exactly the same as they were before mining started.

Rock debris from the removal of overburden cannot be piled as high or graded as steeply as the original mountaintop. The topography ends up being leveled—the mountains are lowered and valleys raised.

To avoid erosion during the reclamation process, soils are heavily compacted and then planted with fast-growing grasses. Trees are sometimes planted as well but do not grow back as quickly in this environment. Those grasses appear in these images as faded green or mottled with pink, compared to the bright green of the pre-mining dense forest.

In this type of landscape, more precipitation becomes runoff than it would be in a forest. Furthermore, species diversity can lag behind natural forests, even decades later. The Sentinel-2 close-up makes that clear. A mined area on the left side of the image has returned to green after it was bright pink starting in 1986 in the Landsat imagery. But the shade of green is not yet the same dark green as intact forest.

In the Athabasca oil sands region of northwestern Alberta, Canada, mining companies are required to restore the disturbed land to be at least as productive as it was before it was mined. Overburden that was removed for surface mining is replaced on top of the sand and sediment layer. Mining companies must ensure the overburden is not contaminated during the storage period.

Native species are then planted, such as white spruce, aspen, dogwood, and blueberry.

For example, a location called Wapisiw Lookout was a tailings pond from 1967 to 1997. The image series shows it later filled in by 2009, and then green by 2011.

Data from Landsat satellites continue to monitor the mining and reclamation of the Athabasca region. Its frequent repeat cycle ensures that the land can be observed as it changes.

Have you noticed that in these images, clouds look white but the ocean looks black? Both are made of the same substance, water—why would they appear as opposite colors?

Landsat satellites see solar energy that reflects off the earth (or atmosphere) and back to the satellite. When light hits water, whether ocean or cloud droplet, most of the light reflects at the same angle it came in, like a basketball bounce-pass. Calm water lets the light bounce away, like a mirror, so little light reflects toward the satellite; the ocean looks dark. But a cloud’s millions of droplets bounce the light around like pinballs, so some light always scatters toward the satellite; therefore, the cloud looks bright. This is the same reason a choppy ocean with whitecaps looks brighter than a calm ocean.

Calaveras Lake and Victor Braunig Lake are artificial lakes that provide cooling water for nearby power plants. The lakes are also popular fishing and boating destinations. Two of the power plants can be seen in the images, in the crooks of the two larger lakes (Calaveras is on the right).

By contrast, Mitchell Lake, west of Braunig Lake, is a natural lake. The shallow lake is on a migratory bird route and is used by over 300 species as a resting point. Because it is shallower than Braunig Lake and Calaveras Lake (average depth less than 8 feet), Mitchell Lake appears slightly blue in some images.

You’ll also notice a major change just west of Mitchell Lake between the 2002 and 2013 images. The smattering of white along the western edge of the 2013 image is Toyota Motor Manufacturing Texas, a manufacturing plant for Toyota pickup trucks. The plant began operations in 2006.

A lot of the urban area consists of large planned communities, often for retirees. Many of these communities incorporate artificial residential lakes. Digging out these lakes provided construction fill for roads and elevated low-lying land for development. The lakes also reduce the risk of urban flooding by capturing storm water runoff, and add aesthetic value.

Comparing the images in this time series, the number of small water bodies increases substantially. The small dark shapes are scattered throughout the green shades that indicate residential areas, along with golf courses, which appear brighter green. The dark green in the lower left is the Loxahatchee National Wildlife Refuge.

Ice shelves act as doorstops. They hold back the glaciers that flow to the ocean and slow them down. Even small ice shelves like Verdi help regulate the volume of ice that glaciers deposit into the ocean.

Evidence of ice shelf instability can be seen in Landsat imagery. As ice shelves become thinner, rifts can form in the ice, a sign of structural weakening. In these images of Verdi, the rifts range in length from 2 to 4 kilometers. The entire shelf width is only about 10 kilometers. Landsats 8 and 9 can monitor Antarctic ice shelves with enough frequency to see if these rifts expand. The size of these rifts along with their rapid development suggests that Verdi is becoming increasingly unstable.

Another characteristic of thinning seen in Verdi is ice front retreat: the result of this retreat is the front boundary of the shelf bows inward toward the center. The Verdi ice front retreated 1.5–2 kilometers from 1973 to 2001. It retreated another 2 kilometers by 2014.

All of this evidence points to the real possibility of Verdi collapsing.

Phnom Penh lies just west of the four-river intersection called the Chattomukh ("Four Faces"). From the northwest and northeast, respectively, flow the Tonle Sap and Mekong Rivers. These waters merge and split into the Basak River and the Mekong, which flow southeast to the South China Sea.

The Mekong River is the 12th longest in the world, flowing 4,200 km from western China to the Mekong Delta in southern Vietnam. Every autumn, monsoon rains are too great for the Mekong to carry, and it floods a large area of Cambodia. This flood even reverses the flow of the Tonle Sab River, northward to the Tonle Sap ("Great Lake"), which can expand to ten times its normal size.

This area receives 152 to 203 cm of rain annually, most of which falls during the southeast monsoons from mid-May to early October. Landsat images are effective for quantifying changes in surface water. The pair of images from 1995 shows the dramatic effect the annual flooding can have.

The modernization of Saudi Arabia has been a recent and rapid phenomenon. Here we see two aspects of this transformation: explosive urbanization and center-pivot irrigation. Both are visible in and near Riyadh from 1972 to 2023.

The growth of Riyadh, the national capital, is dramatic. Its population grew from about half a million in 1972 to over 7 million in 2022. Saudi Arabia experienced urbanization later than many other countries; in the early 1970s, its urban-rural ratio was still about 1:3. By 1990, that had reversed to about 3:1. The cities grew through in-migration from rural areas and from decreases in the death rate while the birth rate remained high. In the mid-1970s, Riyadh’s population was increasing by about 10 percent a year.

The dark red squiggly line that winds through the western part of Riyadh is called the Wadi Hanifa, or the Hanifa Valley. This natural water course drains an area of over 4,000 square kilometers. Riyadh has been working to maintain the Wadi Hanifa as an environmental, recreational, and tourism resource.

Located about 35 kilometers north of Riyadh, King Khalid International Airport opened in 1983, so it only appears in the images after that date. The two parallel runways are each 4,200 meters long. The airport occupies about 225 square kilometers.

The conversion of tropical rain forests to pasture and cropland is having dramatic effects on the environment. Particularly intense and rapid deforestation is taking place in the state of Rondônia, Brazil, part of which is shown in this series of Landsat images.

About 30% (3,562,800 km²) of the world's tropical forests are in Brazil. The estimated average deforestation rate from 1978 to 1988 was 15,000 km² per year. In Rondônia, 67,764 km² of rain forest had been cleared through 2003—an area larger than the U.S. State of West Virginia.

Systematic cutting of forest vegetation starts along roads and then fans out to create the "feather" or "fishbone" pattern, which begins to show in the eastern half of the 1984 image.

The border area of Mauritania and Senegal in westernmost Africa is an example of both expanding irrigation and desertification. The international border between Mauritania and Senegal is the Senegal River, flowing westward and interrupting the arid lands to the north and south. The regional capital of southwestern Mauritania is Rosso, which is on the north bank of the river, and the town of Richard Toll ("Richard's Field" in the Wolof language) is on the south bank. The effects of a highway, which connects the regional capital Rosso to the national capital Nouakchott, on the desert is seen in the close-up images.

In southeastern Kuwait, on the coast of the Persian Gulf, a fascinating transformation is underway. It looks kind of like what you always wished you could build when making sand castles at the beach—an intricate interconnected moat in the sand with perfect circulation to keep the water from becoming stagnant. Only this is on a grander scale.

This is Sabah Al Ahmad Sea City, a city and marine ecosystem being built from scratch. Rather than build artificial islands in the sea to extend the country’s coastline, this project brings the sea to the desert.

Many Kuwaitis aspire to waterside living, and Sea City will provide such opportunities, effectively doubling the length of the country’s coastline. The project’s goal is for most residents to have direct access to a beach. Planners want the city to be the seafront destination of choice for Kuwait.

Sea City is eventually planned for a population of 250,000 and will have 200 kilometers of beaches. The city will also have yachting marinas and retail centers. When finished, Sea City will be about the size of Manhattan.

To build the city, canals are excavated out of the salty marshland. The excavated sand is washed and then used to build up the land for residential development. In fact, the land is being built up above projected sea levels to protect people and property from flooding.

This view also shows an expanding agricultural area along the Saudi Arabian border. In addition, other residential developments crop up in the inland desert areas over time. Just north of Sea City is the Al Zour thermal power plant. This gas-fired power plant and desalination plant were completed in late 2016.

(Black stripes run through some of the images because of the Scan Line Corrector failure on Landsat 7 in May 2003.)

If you like being connected to the world everywhere you go with a smartphone or other device, then you have a desolate salt flat in northern Chile to thank.

The salt flat is the Salar de Atacama, one of the largest sources of lithium, a key ingredient in rechargeable batteries. The rectangular shapes in these Landsat images indicate where lithium mining is taking place. The increasing use of smartphones, laptops, and electric cars that use lithium-ion batteries ensures an ever higher demand for the soft, silvery metal.

The salar is in Chile’s Atacama Desert, probably the driest place on the planet. Water leaves the salar only through evaporation, a process that leaves behind salts. The white color around the edge of the salt flat is clay and carbonate-rich material. The center of the salt flat consists of hard crusts of sodium chloride. Under this crust are brines that contain large amounts of lithium, potassium, magnesium, and boron.

Not completely devoid of a water source, the northern part of the basin is the San Pedro River delta. The San Pedro is an ephemeral stream, delivering small amounts of surface water to the basin from the north. The water originates from the Andes Mountains after infrequent storms. These flows form alluvial fans, visible around the fringes of the salt pan.

The scant vegetation appears red in these images, especially around springs at the northern edge of the salt flat. The salt flat itself covers about 3,000 square kilometers, almost the size of Yosemite National Park in California.

The estuaries of the Saloum River, near the coast in Senegal, are surrounded by mangrove forest. These images show the forests dying between, turning from dark red to gray. The likely cause is a persistent drought, which may have increased the estuary’s salinity beyond the mangroves’ tolerance. However, there are recent indications of mangrove gain in the region.

Lake Urmia is a hypersaline lake. Rivers carry sediments and minerals to the lake, and as the lake water evaporates, the minerals remain. As a result, the salts in the lake become more concentrated and the water becomes increasingly more saline.

As the lake’s water recedes, the salty lakebed is exposed. Light blue or pale shades fringe the lake’s shoreline in these images. These salt flats do not support agriculture, and this salty desert could cause windblown salt to damage nearby fields. A similar phenomenon is happening in the vicinity of the Aral Sea.

Crops are grown near rivers that flow into Lake Urmia. Green fields mark these river deltas, such as the ones shown southeast of the lake. With little precipitation in this region, farming depends on irrigation from the rivers. An increasing population is putting more pressure on water resources. Much of the streamflow from these rivers no longer reaches the lake.

These images show the metropolitan area of San Antonio, Texas. According to the U.S. Census Bureau, the population of the San Antonio metropolitan area was 863,669 in 1970. By 1990, the population had grown to 1.41 million. That growth continued, with increases to 1.71 million in 2000, 2.14 million in 2010, and 2.60 million in 2021. The population change from 1990 to 2021 is an 84% increase, and in 2021, San Antonio ranked 24th in the country in population.

In the lower right corner of the main images, you can see Nicaragua’s San Cristóbal volcano, which shows some activity in two of the images. Ash can be seen in the 1987 and 2000 images thinly streaming from the summit. San Cristóbal is Nicaragua’s highest volcano—its summit is 1,745 meters above sea level. Small to moderate eruptions have been reported since the 16th century.

You might also notice in the 2000 image another active volcano. Telica is southeast of San Cristóbal. The ash streaming from its peak is evidence of its recent activity.

Changes in land use, climate, and population demographics are placing unprecedented demands on water supplies in the United States. Add frequent droughts to that list, and mapping water use in the western United States is becoming increasingly important.

California’s San Joaquin Valley is one of the world’s most productive agricultural regions. Much of that productivity depends on the availability of water for irrigation. Recent prolonged droughts in California have underscored the importance of accurately monitoring changes and trends in water use in order to make well-informed water management decisions.

Landsat images show some change to the farmland in this valley over time. Not visible is exactly how much water was used to irrigate those crops. That’s where evapotranspiration (ET) comes into play.

ET is the combined effect of evaporation from the soil and transpiration from plants. ET is a major part of the hydrologic budget of a watershed. It varies with different climate, vegetation types, and land use.

With ET estimates derived from satellite data, scientists at EROS estimated how much water is being used to water crops. They used a computer model that incorporates Landsat imagery, including the Landsat 8 thermal band, along with climate data to estimate ET for every Landsat scene of the San Joaquin Valley from 1984 to 2014.

They then used the ET results along with precipitation and runoff data to create maps that show water use in the valley over that 31-year time period. The maps show seasonal crop water use in millimeters with enough detail to show individual fields and reveal which crops are using the most, or least, water.

Farther upstream, the San Juan River flows into the Colorado River. In these narrower upstream portions of the rivers, more exposed riverbed appears in the later images.

Follow the San Juan River upstream. It noticeably shrinks by 2005, and it becomes less dark in 2018. Shallower water has more sediment and that appears lighter.

Taking a closer look at the San Julian settlements reveals the pattern of deforestation more clearly.

Most of the settlers were from Bolivia’s western highlands, and the rest were poor farmers from the Santa Cruz department. A prolonged drought in the 1980s followed by an economic crisis led to further migration to the San Julian settlements. Settlement was much slower than expected. So even though the satellite images show rapid expansion, growth was planned to be even more rapid.

The farmland is organized in a distinct pattern of nucleos. A nucleo is a square block of land, about 2,000 hectares in size. Two to four hectares in the center are designated as communal land, where a deep well for water is located. Some centers have school buildings, soccer fields, marketing centers, medical treatment posts, or cooperative stores. Planners recognized the importance of soccer by making the cancha, or soccer field, a part of the nucleo center layout in each settlement.

The individual farm plots radiate outward from the central communal area and each covers just under 50 hectares. The major crops are maize, sunflowers, and soybeans. The nucleo pattern provides an area of concentrated social and economic interaction.

In the 1960s, San Julian, Bolivia, was nearly inaccessible, located deep in the thick Amazon forest. The few roads that existed were only passable during the dry season. The relatively flat lowlands make the region suited to farming. The land can be easily, and relatively cheaply, cleared with heavy machinery. The area also receives abundant rainfall and can support two growing seasons.

With financial help from international organizations, Bolivia started a program to settle the area, to drive development and improve the economy. This development, however, has resulted in the deforestation of the rain forest. The San Julian settlements are conspicuous in the upper left of these Landsat images as one unique type of deforestation pattern.

Other deforestation patterns emerge in the rest of the time series of images in the Bolivian department called Santa Cruz. The region has transformed from dense forest into a grid-patterned expanse of agricultural lands. Many of the fields are soybeans cultivated for export. Prices have been good for soybeans, and they are relatively easy to grow.

The rapid population growth of Santiago, Chile’s capital, has brought a series of problems for the city, all of which were complicated by Chile’s unusual geography.

One Landsat image spans the breadth of this narrow country, from the Pacific Ocean to Argentina. These images were taken near the end of the warm, dry summer; the mountains show only a dull red vegetation signature, and a fire appears in the 1989 image. But there are still patches of snow visible in the Andes Mountains, over 6,000 meters above sea level.

In contrast, the Central Valley, between the Andes and the coastal range, shows a bright red signal from agriculture. Rivers feed into a network of canals irrigating vineyards, fruits, and vegetables. This Central Valley is the heartland of Chile and the home to 70–80% of its people.

With rapid industrialization after World War II, Chile’s population urbanized earlier than many other countries, already 68% urban by 1960, 81% by 1980, and 89% by 2010. Santiago itself contains more than a third of all Chileans, and its share of the country’s economic activity is even greater.

One result was some of the world’s worst air pollution. Santiago’s view of the mountains was often blocked by smog trapped in the valley by the mountains themselves. The government imposed carless Sunday mornings, regulation of the city’s 11,000 private buses, and other remedies. By the mid-1990s the air had improved.

Landsat 8 has a 16-day repeat cycle. That means it images the same spot on the ground every 16 days. However, there is some overlap at the sides of the images, and that overlap increases at higher latitudes.

Here in northern Greenland, at about 81 degrees north latitude, the repeat cycle of Landsat 8 is in reality much more frequent than every 16 days during spring, summer, and fall. Displayed in this section are several clear images available from Landsat 8 of Petermann Glacier from May 23 to September 19, 2014. As you can see by the acquisition dates, Landsat visits this spot more frequently than every 16 days. This was especially true in August and September, 2014, when there were more non-cloudy days.

Seasonal changes are noticeable in this image series. For example, the high cliffs on the west side of Petermann Glacier cast longer shadows in September than on June 24, close to the summer solstice.

The patterns in the ice also change throughout the year. The amount of ice in the water diminishes through September, and by the next May will be packed in again. On the ground, the amount of snow cover also decreases, but the ice fields remain. The snow cover does begin increasing again in the late September images indicating winter is returning. The later images are also darker as the sun approaches a lower angle in the sky as it gets closer to the autumnal equinox.

During the flood season, the delta can grow to 20,000 square kilometers (7,700 square miles). During the dry season, it can shrink to 3,900 square kilometers (1,500 square miles). The flatness of the delta region—it drops only 8 meters (26 feet) over its entire length—leads to this large spread of water.

In the images, dark blue to black areas represent open water. The water expands and then noticeably begins shrinking in December. Any bright green, which is actively growing vegetation, also begins to diminish by late December. Dark blotches in the June image are bare ground. And this is roughly what it will look like again the following June.

These 2014 images show a flood level that was close to average.

While the overall trend in this time series is a shrinking lake, the northern portion has some water in the later images, but it varies widely. Water levels there remained below the 1900–2010 mean and far below what it was in the 1960s.

The region has a short rainy season, and changes in rainfall amounts can greatly affect the water supply. About 90% of the rain falls from June to September, but the lake doesn’t rise until November. This is the natural lag time of water flowing through the Chari River system.

In this series of Landsat images from 2017–2018, the water rises through February and then tapers off slowly for several months. So the rise in water levels actually occurs during the dry season.

Water displays as dark blue, and wetlands are green. The brighter speckles are sand dune islands. Landsat will continue to provide information about Lake Chad’s changes, its infrared imaging capability accurately delineating land, water, and wetland.

Historical images from the USGS EROS archive show the changing cratered landscape. A 1952 aerial photo shows that nuclear testing had already begun. A declassified satellite image from 1965 shows a more heavily cratered landscape and reveals the largest of them.

A 104-kiloton nuclear device was detonated 635 feet underground on July 6, 1962. The explosion created a cavity that the surface soil collapsed into. The resulting crater, named Sedan crater, is 1,280 feet wide and 320 feet deep.

Sedan crater was not the result of a weapons test, but a part of Operation Plowshare, which explored the use of nuclear detonations for peaceful purposes. The idea was to use them in the construction of canals, harbors, quarries, or other projects requiring excavation. Sedan was the second and largest Plowshare experiment.

These tests went about as you would expect. A nuclear explosion could excavate a large amount of material pretty quickly, but the radiation left behind made it glaringly impractical.

In September 1999, engineers at EROS were reviewing Landsat 7 sensor output. An image grabbed their attention. Over Selkirk Island, about 500 miles off the coast of Chile, they noticed an unusual cloud pattern. They referred the image to EROS scientists, who identified the striking series of swirls as a “Karman vortex street,” a fluid flow pattern rarely seen so clearly outside of a laboratory.

How did these Karman vortices develop? Selkirk Island is the tip of a volcanic peak, rising sharply from the ocean, its steep sides critical to the formation of these vortices. Though covering only 33 square miles, the island rises over a mile into the sky.

On the day Landsat 7 acquired this image, the wind was carrying northward a layer of stratocumulus clouds (flat-bottomed puffballs). The mile-high island caused this cloud layer to slow about the island, while remaining fast farther out on either side. So on each “wing,” left and right, the air started rotating toward the inside—clockwise on the left, counter-clockwise on the right. The rotational momentum made each side swirl in on itself.

The whorl-cores were clear because the swirling pulled dry, clear air (from above or below) into the wet layer, a bit like the funnel formed when you stir up a pitcher of orange juice. These clear, spinning pockets trailed off down the “street” from the island like soap bubbles from a toy wand—drifting downwind, weakening, filling with clouds, and breaking up.

We ordinarily show as few clouds as possible in Earthshots because they block our view of the land, but in this case they do have scientific, as well as aesthetic, value. The American Meteorological Society featured the Selkirk image on the cover of their monthly bulletin. This image also became one of the earliest selections in the Earth As Art collection.

On the Seno Plain of Mali, the population has more than doubled since 1972. In this wide view of the region, the Seno Plain sweeps from lower left to upper right. The feature to the left is the Bandiagara escarpment, with a rocky plateau to the west. The rocky surface on this plateau is not suitable for agriculture. So the plain, which is 200 meters lower than the plateau, is where there is increasing demand for agricultural land as the population grows.

Growing vegetation is indicated by red tones in these Landsat images, which are visible and near-infrared composites. These images are from the dry season, so cropland is indicated by bright tones.

Villages are scattered throughout the Seno Plain. They increase in size throughout the series of images. In the 1972 and 1986 images, the villages are the dark spots surrounded by a light color. Those light areas are cropland surrounding each village. In the 2016 image, the light-colored areas merge, and the dark spots stand out as the location of the villages. The population of these villages ranges from a few hundred to several thousand.

A megacity is a region that has a population greater than 10 million. It seems the term was created for cities like Shanghai, China. In 2000, the fast-growing city was home to 16.4 million people. Shanghai’s population exceeded 24 million in 2023. It’s the 2nd largest city in China and 7th largest in the world.

Shanghai sits on the Yangtze River delta along China’s eastern coast. Much of Shanghai’s growth has been in suburban and outlying districts. The Landsat imagery makes this clear as the smaller populated areas outside of Shanghai expand and then are absorbed by the urban expansion. Growth is also notable along transportation systems. Landsat data provides insight into urban planning and sustainable development.

The Landsat satellites were designed to detect landscape changes over time. However, sometimes what Landsat needs to see on the Earth’s surface is no change at all.

This is the story of a key Landsat calibration test site that is being retired as a test site because of the extensive land use change taking place in that area.

The population of China has been urbanizing at a rapid rate. In 1978, less than 20% of China’s population lived in cities. In 2015, more than 55% of the population of China was urban, and that rate is climbing. By 2030, the country’s urbanization is projected to reach 70%. That will be about 1 billion people living in cities in China.