Sea ice around Antarctica has shrunk to the smallest annual extent on record after years of resisting a trend of man-made global warming, preliminary United States satellite data showed on Tuesday.

Ice floating around the frozen continent usually melts to its smallest for the year around the end of February, the southern hemisphere summer, before expanding again as the autumn chill sets in.

This year, sea ice extent contracted to 2.287 million square kilometers on Feb 13, according to daily data from the US National Snow and Ice Data Center.