Recent observations of Antarctic sea ice

Antarctic sea-ice is potentially one of the most sensitive global warming indicators. Some re- cent studies using coupled ocean-atmosphere general circulation models suggest that C0,- induced warming and concomitant sea-ice re- duction might be less marked than in the Arctic (Gordon and O’Farrell 1997); certainly the moderating influence of the Southern Ocean as a heat store must be considered. On the other hand, because Antarctic sea-ice is generally much thinner (typically 0.3-1.0m) than its boreal counterpart (about 3.0m), changes in its extent are possibly more temperature-sensitive than in the Arctic (Rind zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA et zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA al. 1997). A twofold response involving a decrease in sea-ice extent near the Antarctic Peninsula zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA (AP) and a more general increase elsewhere around Antarctica might result from an enhanced maritime-conti- nental climate regime (Stammerjohn and Smith 1997). According to this idea, for which there is some observational evidence, increased precipitation may freshen the Southern Ocean surface layer, lower the sea surface temperature (SST) and strengthen the prevailing westerly winds in the Southern Circumpolar Trough (polar cyclone belt) - the position of which may also change