Ice-lake interactions: How does it affect the ice sheet retreat?

Ice-dammed lakes expedite glacier retreat, leading to the expansion of lakes and an elevated risk of Glacial Lake Outburst Floods (GLOFs), and delay the freshwater inflow to the ocean. The escalating number of ice-dammed lakes in Greenland, High Mountain Asia, and Patagonia, driven by the swift retreat of glaciers amid rapid warming, poses a significant threat of natural disasters. Despite extensive research on marine-terminating glaciers, the dynamics of lacustrine-terminating glaciers remain poorly understood. Geological evidence indicates the rapid retreat of the Fennoscandian ice sheet, marked by the formation, expansion, and drainage of ice-dammed proglacial lakes. This underscores a comprehensive investigation into ice-dammed lake-glacier interactions spanning both Paleo- and Contemporary ice sheets. The deglaciation and ice-lake interactions of the Fennoscandian Ice Sheet (FIS) provide a valuable analogue for projecting the future retreat of the Greenland ice sheet, where a manifold increase in the number and volume of ice-dammed lakes is anticipated.

One key aspect of proglacial lake damming is that they may episodically drain; and drainage may be more or less instantaneous. Our study investigates first the effect of lake size, and secondly the effect of sudden lake drainage, on the dynamics of lake-terminating ice sheet outlets using the Ice-sheet and Sea-level System Model (ISSM). Our findings reveal significant differences in the dynamics of land- and lake-terminating glaciers without calving, with the magnitude of differences varying with the lake level. Furthermore, we observed abrupt changes in the deviatoric stress at the front during rapid lake drainage, which could potentially trigger cliff collapse and accelerate ice sheet retreat.