Reply on RC1

Abstract

<strong class="journal-contentHeaderColor">Abstract.</strong> Glacial Isostatic Adjustment (GIA) has a stabilizing effect on the evolution of the Antarctic Ice Sheet by reducing the grounding line migration that follows ice melt. The timescale and strength of this feedback depend on the spatially varying viscosity of the Earth&rsquo;s mantle. Most studies assume a relatively high laterally homogenous response time of the bedrock. However, viscosity is spatially variable with a high viscosity beneath East Antarctica, and a low viscosity beneath West Antarctica. For this study, we have developed a new method to couple a 3D GIA model and an ice-sheet model to study the interaction between the Solid Earth and the Antarctic Ice Sheet during the last glacial cycle. The feedback effect into account on a high temporal resolution by using coupling time steps of 500 years. We applied the method using the ice-sheet model ANICE, a 3D GIA FE model, and results from a seismic model to determine the patterns in the viscosity. The results of simulations over the Last Glacial Cycle show that differences in viscosity of an order of magnitude can lead to differences in grounding line position up to 500 km, to differences in ice thickness in the order of 1.5 km. These results underline and quantify the importance of including local GIA feedback effects in ice-sheet models when simulating the Antarctic Ice Sheet evolution over the Last Glacial Cycle.