250 000 years in the history of Greenland's ice sheet
by M. Weis, K. Hutter, R. Calov
Calculations have been conducted for the geometric evolution of the Greenland ice sheet through the last 250 000 years of its climate history. An extended version of Calov's three-dimensional ice-sheet model is used, i.e. ice is modelled as a viscous thermomechanically coupled fluid with power-law rheology underlain by a heat-conducting lithosphere susceptible to bedrock sinking. The shallow-ice approximation is imposed and the simplified equations are numerically integrated by finite-difference approximation using a centred staggered Arakawa grid. This system is driven by data obtained from the European Greenland Ice Gore Project (GRIP). The parameterization of the atmospheric temperature is based on data from Ohmura, precipitation data are taken from Ohmura and Reeh and implemented as shown by Calov. Topographic data for the present observed conditions are those of Letreguilly. The resultant 250 kyear model integrated topography is quite close to that obtained from a steady-state calculation under present conditions. For the calculations presented, Greenland's north dome seems to be more sensitive to changes in precipitation than its south dome. While the height of the north dome is directly related to the atmospheric temperature, the height of the south dome is inversely-related to this variable. In the south, changes in ice dynamics due to a change in ice temperature oppose changes in precipitation. The calculations are visualized in a short video clip that is kept on file with the authors.
