Impacts of surface melt and hydrology on Antarctic ice-shelf dynamics and break-up*

Ice shelves, which are thick floating layers of glacier ice extending from the glaciers on land, buttress much of Antarctica and protect the ice sheet from greater rates of mass loss than it is already experiencing. However, field, remotely-sensed, and modeling based data suggest that the stability of these ice-shelves is threatened due to stress variations associated with surface meltwater ponding and drainage. These processes may initiate meltwater-induced vertical fracturing (‘hydrofracturing’) and iceberg capsize, which may ultimately lead to ice-shelf disintegration. For example, the rapid and widespread collapse of the Larsen B ice shelf in 2002 was likely driven by the drainage of about 3000 lakes via a chain reaction style process.

Surface melting and ponding on the surfaces of Antarctic ice shelves is becoming increasingly widespread, and melt rates are predicted to increase significantly this century. Although the most up to date ice-sheet models do not account for the effects of meltwater ponding on ice-shelf stability explicitly, these models respond dramatically to increased ice-shelf melting, predicting up to 1 m of sea-level contribution from Antarctica this century.

By focusing on a variety of field, remotely-sensed and modeling based case studies drawn from my research, I will present recent progress and future research directions in the rapidly growing field of Antarctic ice-shelf surface hydrology and stability. Such case studies will include: i) the first field-based study of ice-shelf flexure in response to the filling and draining of surface lakes; ii) an optical and microwave satellite data based study showing 32-year record melt on the George VI Ice Shelf in the 2019/2020 austral summer; and iii) results from a new process-scale ice shelf model that simulates, for the first time, both ice flow and viscoelastic flexure in response to a variety of surface meltwater phenomena.