Abstract
Antarctic Ice Sheet projections show the highest sensitivity to
increased basal melting in the Amundsen Sea sector. However, little is
known about the processes controlling future increase in melt rates. We
build an ensemble of three ocean–sea-ice–ice-shelf simulations for
both the recent decades and the late 21st century, constrained by
regional atmosphere simulations and the multi-model mean climate change
of the 5th Climate Model Intercomparison Project under the RCP8.5
scenario. The ice shelf melt rates are typically multiplied by 1.4 to
2.2 from present day to future, for a total basal mass loss increased by
347Gt/yr. This is approximately equally explained by advection of warmer
water from remote locations and by regional changes in Ekman downwelling
and in the ice-shelf melt-induced circulation, while increased iceberg
melt plays no significant role. Our simulations suggest that high-end
melt projections previously used to constrain recent sea level
projections may have been significantly overestimated.