The response of the Greenland ice sheet to climate changes in the 21st century by interactive coupling of an AOGCM with a thermomechanical ice-sheet model

Abstract

We present results from a greenhouse warming experiment obtained from an atmosphere-ocean-sea-ice general circulation model that is interactively coupled with a three-dimensional model of the Greenland ice sheet. The experiment covers the period 1970-2099 and is driven by the mid-range Intergovernmental Panel on Climate Change SRESB2 scenario. The Greenland model is a thermomechanical high-resolution (20 km) model coupled with a viscoelastic bedrock model. The melt-and-runoff model is based on the positive degree-day method and includes meltwater retention in the snowpack and the formation of superimposed ice. The atmospheric-oceanic general circulation model (AOGCM) is a coarse-resolution model without flux correction based on the Laboratoire de Météorologie Dynamique (Paris) LMD 5.3 atmospheric model coupled with a primitive-equation, free-surface oceanic component incorporating sea ice (coupled large-scale ice-ocean (CLIO). By 2100, average Greenland annual temperature is found to rise by about 4.5°C and mean precipitation by about 35%. The total fresh-water flux approximately doubles over this period due to increased runoff from the ice sheet and the ice-free land, but the calving rate is found to decrease by 25%. The ice sheet shrinks equivalent to 4 cm of sea-level rise. The contribution from the background evolution is not more than 50% of the total predicted sea-level rise. We did not find significant changes in the patterns of climate change over the North Atlantic region compared with a climate-change run without Greenland fresh-water feedback.