Investigating Basal Thaw as a Mechanism of Ice Mass Loss in Antarctica

Abstract:

The thermal regime at the ice-bed interface exerts a fundamental control on ice flow. While much of the Antarctic ice sheet is frozen to its bed, regions where the bed is thawed can have a profound influence on the rate of basal sliding and ice flow. Thawed bed regions are found in parts of coastal Antarctica, beneath fast flowing glaciers and ice streams, and in much of West Antarctica. In some of these regions, glaciers and ice streams with thawed beds are interleaved by patches of frozen bed. We investigate how the ice sheet could respond if regions where the ice-bed interface is just below the temperature melting point transitioned to being thawed. Using the JPL/UCI Ice Sheet System Model (ISSM), we identify where the base of the Antarctic ice sheet is just below the melting point temperature. We then perform transient experiments over century timescales to explore how thawing of these regions could perturb the ice sheet's evolution. We examine mass loss and contribution to sea level rise that could result from dynamic changes in response to basal thermal regime change in Antarctica. We also examine which drainage basins could be most vulnerable to basal thaw driven changes.