Surface melting over ice shelves and ice sheets as assessed from modeled surface air temperatures

Summer surface melting plays an important role in the evolution of ice shelves and their progenitor ice sheets. To explore the magnitude of surface melt occurring over modern ice shelves and ice sheets in a climate scenario forced by anthropogenic emissions of carbon dioxide (CO₂), a coupled climate model was used to simulate the distribution of summer melt at high latitudes and project the future evolution of high-melt regions in both hemispheres. Forcing of the climate model with CO₂ emissions resulting from combustion of the present-day fossil-fuel resource base resulted in expansion of high-melt regions, as defined by the contour marking 200 positive degree-days per year, in the Northern Hemisphere and the Antarctic Peninsula and the introduction of high summer melt over the Ross, Ronne-Filchner, and Amery ice shelves as well as a large portion of the West Antarctic Ice Sheet (WAIS) and most of the Greenland Ice Sheet (GIS) by the year 2500. Capping CO₂ concentrations at present-day levels avoided significant summer melt over the large Antarctic shelves, the WAIS, and much of the GIS.