The University of Colorado-Boulder researchers said the extent of the Arctic ocean covered by at least 15 percent ice was 5.7 million square miles in March, slightly higher than the record low of 5.6 million square miles measured in March 2006.
The declining sea ice has been blamed on higher winter temperatures in the Arctic, which are believed to be a result of increasing levels of greenhouse gases in the atmosphere and strong natural variability in the ice, said researcher Walt Meier of CU-Boulder's National Snow and Ice Data Center.
A separate review study led by CU-Boulder research scientist Mark Serreze indicated the trends for the extent of Arctic sea-ice have been negative for every month since 1979, when reliable satellite record-keeping efforts began. The September minimum measurements indicate the Arctic has been losing about 38,000 square miles of ice annually.
The review appeared in last month's issue of the journal Science.