The contribution of the Antarctic Ice Sheet to global sea level from the Last Glacial Cycle to the future

The Antarctic Ice Sheet (AIS) is the largest potential contributor to future sea-level rise, with an ice volume equivalent to 58 m of global-mean sea level. However, high uncertainties arise from the representation of key physical processes in ice-sheet models, such as basal sliding, ice-ocean interactions, and feedback mechanisms associated with glacial isostatic adjustment (GIA). Previous studies have estimated the future Antarctic sea-level contribution (SLC) by forcing an ice sheet spun up to a present-day equilibrium state. However, observations of the last decades indicate that the AIS is not in equilibrium, as it is undergoing net mass loss as a result of both ongoing anthropogenic climate change and its long-term adjustment following the last deglaciation. Here, we study the future SLC of the AIS using simulations that span a complete Last Glacial Cycle. To this end, we use the ice-sheet model Yelmo coupled to the GIA model Fastisostasy, and construct an ensemble that accounts for uncertainties in process representation. The model is forced using the PMIP3 ensemble-mean reconstruction of the Last Glacial Maximum (LGM) and the present-day climate, weighted by an index derived from Antarctic ice-core records. The simulations are initiated in the Last Interglacial and evaluated based on their consistency with geological constraints from the LGM and the deglaciation, as well as present-day observations of the AIS. Using these paleo-constrained model configurations, we then investigate the response of the AIS to different future climate-change scenarios.