Modelling global warming and Antarctic sea-ice changes over the past century

Abstract

An atmosphere-sea-ice model is used in combination with results from a coupled atmosphere-ocean-sea-ice model to examine the changes of the Antarctic sea-ice cover influenced by atmospheric circulation associated with the global sea-surface temperature (SST) changes alone over the past century. Using the current climatological SST of Reynolds for forcing, a reasonable seasonal simulation of the Antarctic sea-ice cover for the present climate (including ice concentration, thickness and coverage) is obtained. When global SST anomalies for the past century (derived from the coupled atmosphere-ocean-sea-ice model) are imposed, sea ice becomes more extensive, on the annual average, by 0.7-1.2°of latitude, more compact by about 5-7%, and thicker by 7-13 cm, than at present. These changes are similar to those simulated from changes in greenhouse gases using the coupled atmosphere-ocean-sea-ice model which gave corresponding changes of about 0.8°of latitude in extent, 6% in ice concentration and 12 cm in ice thickness. The simulated change in annual mean global surface temperature by the coupled atmosphere-ocean-sea-ice model was 0.7 K (0.6 K over the ocean including sea ice) which is similar to the observed change. Over the Antarctic the corresponding simulated change is 1.2 K which also appears compatible with observations.