The Antarctic ice cap

The volume of the ice sheet over Antarctica is now about the same as that of the Laurentide ice sheet over North America during the last Ice Age. The average elevation of the continent is 2.2 km, far above the 700 m for others, yet the bedrock elevation of most of Antarctica is near sea level. The atmospheric pressure at the South Pole (at 2,800 m) is about 680 hPa, and at Vostok (3,500 m) about 620 hPa. The extreme temperatures at the South Pole are -14° C to -81° C, and at Vostok -21° C to -89° C.

In total, there is enough snow and ice on Antarctica to raise the sea level by 70 m. The Antarctic ice cap has been present continuously for the last 5 million years and there is no evidence that the ice volume is changing. During the next century, the ice volume could grow a little, on account of global warming (1). The accumulation rate would increase, because warmer air, when saturated, caries more water vapour. But the amount of melting would remain insignificant. The Antarctic accumulation would lower global mean sea level by 0.9 mm/a.

Apart from the inland ice there is sea ice, and ice shelves in relatively shallow bays. The Ross and the Filchner-Rome ice shelves are each the size of France.

(1) Ohmura, A., M. Wild and L. Bengtsson 1996. A possible change in the mass balance of Greenland/Antarctic ice sheets in the coming century. J. Clim., 9, 2124-35.