Dramatic warming in the Arctic is accelerating the melting of snow and ice. The NPS Arctic Inventory and Monitoring Network (ARCN) is using Landsat satellite images to monitor the area of lakes and ponds in the five NPS units in northern Alaska. Water surface area trends were computed using both the new U.S. Geological Survey dynamic water surface extent product and a simpler method based on thresholding the shortwave infrared band of the same Landsat images. The two methods produced generally similar results. During the period for which annual Landsat data were available (2000–2019), most of the study area showed either declining water area or weak trends. The areas with rapidly declining water area had lakes of thermokarst origin in ice-rich permafrost, where sudden lake drainage events due to permafrost thaw were common. The year 2019 had the most lake drainage events of any year in the period 2000–2019, with the great majority of lake drainages occurring in the lowlands of northern Bering Land Bridge National Preserve.
Lake loss in northeastern Bering Land Bridge National Preserve, Alaska. Areas that lost water between 2017 and 2018 are shaded in green, and areas that lost water from 2018 to 2019 are shaded in yellow. Lakes over 5 hectares in area that drained in 2018–2019 are labeled with the area lost, in hectares. Large (> 50 hectares) pre-2017 drained lakes are outlined and labeled with the year in orange. The white lines outline ecological subsections used as analysis areas, and a large parcel of private land is hatched.