Glacial Retreat A Bear Glacier, Alaska, USA story
Glaciers
Water
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.
Location
Aug. 10, 1976, Landsat 2 (path/row 74/18) — Bear Glacier, Alaska, USA
June 18, 1984, Landsat 5 (path/row 69/18) — Bear Glacier, Alaska, USA
Sep. 27, 1994, Landsat 5 (path/row 68/18) — Bear Glacier, Alaska, USA
July 1, 2000, Landsat 7 (path/row 68/18) — Bear Glacier, Alaska, USA
Aug. 5, 2001, Landsat 7 (path/row 68/18) — Bear Glacier, Alaska, USA
June 21, 2005, Landsat 5 (path/row 68/18) — Bear Glacier, Alaska, USA
July 21, 2007, Landsat 7 (path/row 68/18) — Bear Glacier, Alaska, USA
Sep. 15, 2010, Landsat 7 (path/row 68/18) — Bear Glacier, Alaska, USA
Sep. 2, 2014, Landsat 8 (path/row 68/18) — Bear Glacier, Alaska, USA
Sep. 4, 2018, Landsat 8 (path/row 69/18) — Bear Glacier, Alaska, USA
Sept. 9, 2020, Landsat 8 (path/row 69/18) — Bear Glacier, Alaska, USA
Sept. 9, 2020, Landsat 8 (path/row 69/18) — Bear Glacier, Alaska, USA
Bear Glacier, Alaska, USA Additional Imagery & Stories
Bear Glacier Lagoon
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 Glaci...
Glacier Repeat Photography
USGS uses repeat photography of glaciers to quantify changes in glaciers over time. Repeat photography is a technique in which a historical photograph...
Racing Stripes
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 mate...