Photo: Little multi-year ice on the Arctic Ocean in March 2011

This image from the National Snow and Ice Center shows how little multi-year ice (in green) remained in the Arctic at the end of March. New data on ice age shows that the amount of older, thicker ice increased slightly over last year. Ice more than two years old is shown in blue and first-year ice in pink on this image. The amount of older ice remains much lower than in the mid-1980s, and there is still almost none of the oldest ice, older than four years old, that used to dominate much of the Arctic Ocean. Arctic sea ice cover for the month of March 2011 was the second lowest in the satellite record, the NSIDC announced last week. Air temperatures over most of the Arctic Ocean were above normal. (IMAGE/NSIDC)