Long-Term Increase in Antarctic Ice Sheet Vulnerability Driven by Bed Topography Evolution

Abstract

Ice sheet behavior is strongly influenced by the bed topography. However, the effect of the progressive temporal evolution of Antarctica's subglacial landscape on the sensitivity of the Antarctic Ice Sheet (AIS) to climatic and oceanic change has yet to be fully quantified. Here we investigate the evolving sensitivity of the AIS using a series of data-constrained reconstructions of Antarctic paleotopography since glacial inception at the Eocene-Oligocene transition. We use a numerical ice sheet model to subject the AIS to schematic climate and ocean warming experiments and find that bed topographic evolution causes a doubling in ice volume loss and equivalent global sea level rise. Glacial erosion is primarily responsible for enhanced ice sheet retreat via the development of increasingly low-lying and reverse sloping beds over time, particularly within near-coastal subglacial basins. We conclude that AIS sensitivity to climate and ocean forcing has been substantially amplified by long-term landscape evolution.