Role of buttressing in the dynamic response to Western Antarctic Peninsula ice shelf collapse

Ice shelves on the western Antarctic Peninsula have partially or completely disappeared due to widespread thinning and retreat. The loss of floating ice results in a reduction of the buttressing on the upstream grounded ice body. As a consequence, tributary glaciers are accelerating and retreating further, leading to increased ice discharge and, in turn, an increased contribution to sea-level rise. Improving projections of the rate of sea-level rise from the area demands an in-depth understanding of the current mechanisms at play.

In order to gain this, we aim to quantify and characterise the buttressing effect of the ice shelves. To achieve this, we model hypothetical upper-end scenarios by either an immediate complete collapse of all floating ice or a sustained extreme melting. The main focus here is on the stability of the tributary glaciers and the ability of the ice shelf to rebuild itself.

To run the scenarios, we operate ISSM based on surface and basal topography from BedMachine and MEaSURE velocities. A Shallow-Shelf-Approximation with Budd and Weertman sliding laws, Beckmann and Goosse basal forcing parameterisation and von Mises calving is used. To initialise the retreat scenarios, we determine the basal friction coefficient of the grounded area and the ice shelf rheology using a joint inversion technique with regularisation.