First Regional Inventory of Glacial Lake Flooding in Alaska and Canada

The Cryosphere, 25 January 2022

Alaska and northwestern Canada contain more than 27,000 glaciers, which account for the second-largest area of ice in the world outside of Greenland and Antarctica. “Ice-marginal” lakes form along the edges of these glaciers when their outflow is dammed by either ice or sediment deposits. Glacial lakes with different types of dams respond differently to climate change. As global temperatures rise, the flow of meltwater from Alaskan and Canadian glaciers has increased, causing ice dams to collapse and sending massive volumes of water downstream. These floods can have devastating impacts on nearby ecosystems, infrastructure, and communities. Since 1984, accelerated ice loss has decreased the number of ice-dammed lakes by 9%, while increasing the number of sedimentary-dammed lakes by nearly 90%. In the past, ice-dammed lakes have resulted in the greatest number of outburst floods in this region, sometimes multiple times each season as ice dams burst and re-form. Sediment dams however dominate in other regions such as the Himalayas, and result in massive flooding and landslide events in connection with extreme rainfall and springtime melt. With glaciers retreating and more lakes forming due to warming temperatures, authors highlight the need to better understand the drivers of glacial lake flooding in the region, in order to better prepare for future impacts of climate change on vulnerable communities.