A FINITE-ELEMENT MODEL OF ANTARCTICA - SENSITIVITY TEST FOR METEOROLOGICAL MASS-BALANCE RELATIONSHIP

A finite-clement solution of the time-dependent mass-continuity equation for column-averaged ice-sheet flow and sliding is applied to the Antarctic ice sheet. First, a calibration of the model to the steady-state present ice-sheet configuration is presented. With fitted values of the parameters describing the regions of sliding, the degree of bed coupling and the ice hardness, a change in the mean annual sea-level temperature is used to simulate variation of the climatic conditions over Antarctica for both warming and cooling of the climate. Paradoxically, a climate warming of up to 9 deg leads to an increase in ice volume, while cooling leads to decreasing ice volume as long as the present margins of Antarctica are maintained. Some extreme simulations of the Antarctic ice sheet for ''maximum over-riding'' and ''minimum warm climate'' are shown for situations where the present bed conditions are altered. Finally, a time-dependent simulation shows the response of the ice-sheet system to cyclical variations in the simulated climate, demonstrating the lag of the ice-sheet response to be approximately 2700 years.