Modelling the evolution of the Antarctic Ice Sheet since the last interglacial

Maris, M. N. A. Ligtenberg, S. R. M. Crucifix, Michel [UCL] de Boer, B. Oerlemans, J.

We present the effects of changing two sliding parameters, a deformational velocity parameter and two bedrock deflection parameters on the evolution of the Antarctic Ice Sheet over the period from the last interglacial until the present. These sensitivity experiments have been conducted by running the ice-dynamical model ANICE forward in time. The climatological forcing over time is established by interpolating between two climate states from a regional climate model over time. The interpolation is done in such a way that both temperature and surface mass balance follow the Epica Dome C ice-core proxy record for temperature. We have determined an optimal set of parameter values, for which a realistic grounding line retreat history and present-day ice sheet can be simulated, the simulation with this set of parameter values is defined as the reference simulation. An increase of sliding with respect to this reference simulation leads to a decrease of the Antarctic ice volume due to enhanced ice velocities on mainly the West Antarctic Ice Sheet. The effect of changing the deformational velocity parameter mainly yields a change in East-Antarctic ice volume. Furthermore, we have found a minimum in the Antarctic ice volume during the mid-Holocene. This is a robust feature in our model results, where the strength and the timing of this minimum are both dependent on the investigated parameters. More sliding and a slower responding bedrock lead to a stronger minimum which emerges at an earlier time. From the model results we conclude that the Antarctic Ice Sheet has contributed 10.7 ± 1.3 m of eustatic sea level to the global ocean from the Last Glacial Maximum (about 16 kyr ago for the Antarctic Ice Sheet) until the present.