The role of ice-dammed lakes in ice sheet demise

Reconstructing the co-evolution of ice-dammed lakes and the retreating Fennoscandian ice sheet in the Scandinavian mountains.

As high rates of surface melting force the Greenland ice sheet to retreat over its underlying rugged topography, large meltwater lakes will likely become dammed between the retreating ice margin and the coastal mountains. Swathes of the ice margin will change from land- to lake-terminating, with poorly understood consequences for ice margin behaviour and the ice sheet’s future stability. This project investigates the effect of ice-dammed lakes on an ice sheet’s demise, using the analogue of the last Scandinavian ice sheet. In the later stages of its decay, large meltwater lakes were dammed between the Scandinavian ice sheet in the east and the mountains in the west, under a rapidly warming climate. However, the spatio-temporal distribution of both ice and lakes is very poorly known, and the dynamics of the coupling between these systems is an outstanding research question that is key to projecting Greenland’s contribution to future sea-level rise. Landform mapping from high-resolution LiDAR imagery shows great potential for delineating the palaeo-extents, drainage and retreat behaviour of both ice and lakes, and will be used to reconstruct the co-evolution of ice-dammed lakes and ice sheet demise in Scandinavia. An extensive sediment sampling campaign will tightly constrain timing and rates of change. We will use this geological reconstruction to inform and validate ice sheet model simulations aimed at assessing an ice sheet's sensitivity to ice-dammed lake-modulated retreat.