Regional Sea Level Changes for the Twentieth and the Twenty-First Centuries Induced by the Regional Variability in Greenland Ice Sheet Surface Mass Loss

Surface mass balance (SMB) variations of the Greenland ice sheet (GrIS) have been identified as an important contributor to contemporary and projected global mean sea level variations, but their impact on the regional sea level change pattern is still poorly known. This study proposes estimates of GrIS SMB over 19002100 based on the output of 32 atmosphere-ocean general circulation models and Earth system models involved in phase 5 of the Climate Model Intercomparison Project (CMIP5). It is based on a downscaling technique calibrated against the Modele Atmospherique Regional (MAR) regional climate model and it provides an ensemble of 32 Greenland SMB estimates for each Greenland major drainage basin. Because the GrIS SMB does not respond uniformly to greenhouse gas (GHG) emissions, the southern part of the GrIS is more sensitive to climate warming. This study shows that this part should be in imbalance in the twenty-first century sooner than the northern part. This regional variability significantly affects the associated relative sea level pattern over the entire ocean and particularly along the U.S. East Coast and the northern coast of Europe. This highlights the necessity of taking into account GrIS regional SMB changes to evaluate accurately relative sea level changes in future projections.