The thermomechanical response of the Greenland ice sheet to various climate scenarios

Using a three dimensional numerical model for land based ice sheets in the shallow ice approximation simulations are performed to determine the velocity and temperature distributions within the Greenland Ice Sheet through time for various climate scenarios. The ice is treated as a theologically nonlinear heat conducting viscous fluid and the substrate is a heat conducting rigid solid. This system is fed from above by prescribing as the climatic inputs the atmospheric temperature and the accumulation-ablation-rate functions at the free surface and from below by the geothermal heat. We present the governing equations in the shallow-ice approximation, discuss the parameterizations used in the descriptions of the ice-surface temperature and accumulation-ablation functions, briefly state how the complicated initial boundary value problem is numerically solved, and how the input data that are available from measurements are implemented. Results of preliminary calculations disclose how the model performs and delimit its validity. We study the role played by basal sliding and make clear that sliding should be accounted for where ever the basal ice is temperate and that the frictional heat generated in this sliding is thermomechanically significant, We also study the reaction of the Greenland Ice Sheet to various climate scenarios and make clear that today's thermal regime depends significantly upon the prior climate history, Moreover, the thermomechanical properties of the ice are equally significant as is the thermal interaction of the Ice Sheet with the rockbed beneath.