Results of the ISMIP6 Standalone Greenland Ice Sheet Projections

The Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) is a community effort that aims at improving estimates of the future sea-level contribution from the Greenland and Antarctic ice sheets und associated uncertainties. For the standalone Greenland ice sheet projections presented here, an ensemble of ice sheet models is forced with atmospheric and oceanic output from a set of global climate models (GCMs) over the 21st century. Atmospheric forcing consists of anomalies of surface mass balance, obtained from a regional climate model forced by GCM output. Oceanic forcing consists of a prescribed retreat for marine-terminating outlet glaciers based on an empirically derived parameterisation taking into account changes in ocean temperature and surface meltwater runoff. Alternatively, ocean temperature changes and runoff are used to drive physically-based calving parameterisations. We present results of Greenland ice sheet changes and sea-level contributions for the scenarios RCP8.5 and RCP2.6. Our analysis is focused on understanding ice sheet model differences and characterising uncertainties due to forcing, initial ice sheet state and modelling choices.