Thermokarst Lakes: Dramatic increases in the removal of thermokarst lakes from the Canadian Arctic Landscape (TLRemoval)

Many areas of the Arctic are dominated by immense numbers of lakes covering up to 50% of the land area. These lakes provide important habitat for fish, waterfowl and mammals and influence cultural well-being through travel, fishing, and hunting. Most of these lakes formed from melt of massive ground ice over past millennia and are termed thermokarst lakes. These thermokarst lakes are susceptible to a process termed catastrophic thermokarst lake drainage, where melting of massive ground ice near the lake outlet results in the development of a drainage channel that allows emptying of the lake in a few days , and often in less than a day. These drainage events result in: the creation of drained thermokarst lake basins; extreme floods that are a risk to people and infrastructure; new terrestrial habitat; and destruction of fish habitat. Our research has shown that lake drainage declined over the period 1950 to 2000 but tripled over the last 15 years. While the cause of these changes could be attributed to climate warming, permafrost thaw, and/or increased beaver damming, the details and controlling processes are poorly understood. The recent rapid increase in drainage suggests that a threshold has been crossed and raises key questions about the long-term viability of thermokarst lakes and the impacts on ecosystem services they provide. Our proposed study will build on our studies of beaver and climate impacts in this region and answer key questions about past and future causes of lake drainage in the western Canadian Arctic.