| Popis: |
As ice thins and retreats due to climate change, glacial lakes can form and grow. Rapid lake drainage can produce devastating outburst floods leading many to propose that hazards from glacial lakes are increasing. Outburst flood compilations do show an increase in the number of events documented over time, however, recent studies attribute such trends to observational bias. This leaves large uncertainty about current and future glacial-lake hazards. Here, we focus on ice-dammed lake drainages in Alaska, as a third of documented events globally occurred in this region. Using multitemporal satellite imagery (Landsat and Sentinel-2), we documented 1150 drainages from 106 lakes over 1985–2020. Accounting for the increase in satellite imagery availability over time, we find no temporal trend in drainage frequency. Furthermore, 70% of lakes decreased in estimated volume and peak discharge since the 1960s, and nearly a third of lakes released earlier through time. These results suggest a decrease in overall regional flood hazard from ice-dammed lakes and motivates an unbiased look at other regions. |
