Ice-dammed lake-glacier interactions: Modelling the impact on Fennoscandian 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. In the geological record, evidence indicates the rapid retreat of the Fennoscandian ice sheet, marked by the formation, expansion, and drainage of large (10s-1000s km2 surface area and up to 100s m deep) ice-dammed proglacial lakes along the entire length of the late-deglacial ice margin. 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. Despite extensive research on marine-terminating glaciers, the dynamics of lacustrine-terminating glaciers remain poorly understood. While there are some notable differences in thermo-mechanical processes between marine and lacustrine glaciers, a significant contrast lies in the fact that the calving of lake-terminating glaciers is governed by the stress balance induced by rapidly fluctuating lake levels and thermodynamics inherent of lakes. Our study delves into accessing the impact of critical factors, such as lake size and bathymetry, on the retreat of the Fennoscandian Ice Sheet, using the Ice-sheet and Sea-level System Model (ISSM). Furthermore, we aim to evaluate the influence of calving, subaqueous melt, and rapidly fluctuating lake levels on the FIS retreat. The model's accuracy will be ensured through calibration and validation against geologically reconstructed ice sheet boundaries and lake levels.