Antarctic Ice Sheet response over the next 10,000 years: ice sheet dynamics interacting with solid Earth deformations and sea-level change

Antarctica has the largest potential contribution to sea-level change within the modern cryosphere. Therefore, reliable predictions of future sea-level change from the Antarctic Ice Sheet are crucial. Ice sheet interactions with other Earth system components are crucial for making accurate predictions of sea-level change, as relevant interactive feedbacks can amplify or dampen the anthropogenic induced effects and affect associated response time scales. In most ice sheet model projections so far, models generally assume constant bed topography and sea level. Neglecting the stabilizing sea-level feedback due to glacial isostatic adjustment (GIA), i.e., gravitationally, rotationally, and deformationally (GRD) consistent deformations of the solid Earth and sea level change, tends to overestimate the Antarctic Ice Sheet’s contribution to sea level rise on centennial timescales, particularly in regions with very low mantle viscosities and a thin lithosphere. 

 

As part of the PalMod project, we present first results of multi-millennial future simulations with the interactively coupled Parallel Ice Sheet Model (PISM), which represents ice sheet dynamics, together with two glacial isostatic adjustment (GIA) models of different complexity: VILMA (VIscoelastic Lithosphere and MAntle model) and the Lingle–Clark (LC) model. For climatic forcing, we used surface temperature and surface mass balance from the regional climate model RACMO, forced by the climate model CESM2-WACCM, while long-term climate evolution was taken from CLIMBER-X. VILMA is applied as a global GIA model that captures all GRD components and accounts for the 3-dimensional Earth structure. The LC model, which is often used in ice sheet modelling, represents a regional viscoelastic GIA model with constant values for upper-mantle viscosity and lithosphere thickness and only accounts for vertical land motion. The simulations cover the period from the pre-industrial era up to the year 10,000. The projections assess the influence of different Earth structures on ice sheet mass changes, which we show result in particularly different trajectories on the longer time scales.