OBSERVED HEMISPHERIC-ASYMMETRY IN GLOBAL SEA-ICE CHANGES

From November 1978 through December 1996, the areal extent of sea ice decreased by 2.9 +/- 0.4 percent per decade in the Arctic and increase d by 1.3 +/- 0.2 percent per decade in the Antarctic, The observed hem ispheric asymmetry in these trends is consistent with a modeled respon se to a carbon dioxide-induced climate warming. The interannual variat ions, which are 2.3 percent of the annual mean in the Arctic, with a p redominant period of about 5 years, and 3.4 percent of the annual mean in the Antarctic, with a predominant period of about 3 years, are unc orrelated.