Mass loss of ice sheets leads to the regional uplift of the Earth’s solid surface and drawdown of the gravitational equipotential surface on which sea surface height lies, inducing sea-level fall near the retreating ice sheet. Locally falling sea level can be an important stabilizing factor for ice sheets at centennial timescales, especially in West Antarctica where the ice sheet is marine based and thus sensitive to ocean depth. However, these sea-level feedbacks were not included in a recent ice-sheet model intercomparison through 2100 used by IPCC AR6 (Ice Sheet Model Intercomparison Project for CMIP6: ISMIP6).

In this work, we couple the US Department of Energy’s MPAS-Albany Land Ice model and a 1D sea-level model to assess the impact of regional sea-level change on the Antarctic Ice Sheet. We perform coupled simulations of Antarctica under the newly released ISMIP6 protocol in which climate forcing is extended to 2300. We also consider the impact of regional sea-level changes on ice-shelf basal melt rates through changes in ocean bathymetry, which alter the distribution of ocean temperature and salinity reaching the ice-shelf base. We do so by adjusting ocean bathymetry for modeled sea-level changes prior to the extrapolation of temperature and salinity into ice-shelf cavities in the ISMIP6 protocol. We hypothesize that regional sea-level fall associated with ice-sheet melting will lead to a non-negligible reduction in mass loss from the Antarctic Ice Sheet over the coming centuries, both directly due to the stabilizing effect on ice dynamics and indirectly due to a reduction in basal melt rates.