Arctic shrinkage

Arctic shrinkage is the marked decrease in Arctic sea ice and the observed melting of the Greenland Ice Sheet in recent years. Computer models predict that the sea ice area will continue to shrink in the future, though there is no consensus on when the Arctic Ocean might become ice-free in summer; a common theory estimates between 2040 and 2100. Scientific analysis currently has no evidence of seasonally ice-free Arctic over more than 700,000 years, although there were warmer periods. Scientists are studying possible cause and effect factors such as unusual wind patterns, rising Arctic temperatures, or shifting water circulation.

According to the Intergovernmental Panel on Climate Change, "warming in the Arctic, as indicated by daily maximum and minimum temperatures, has been as great as in any other part of the world." Reduction of the area of Arctic sea ice means less solar energy is reflected back into space, thus accelerating the reduction.

2007 saw a record low in summer sea ice. Most of the newly melted area refroze, and the iced area was near normal during the winter of 2007-2008. However the amount of thick perennial ice was below levels measured in the previous winter.

In February 2008, Josefino Comiso, a senior research scientist with the Cryospheric Sciences Branch of NASA's Goddard Space Flight Center in Maryland, commented about low temperatures this winter in the Arctic: "It's nice to know that the ice is recovering....That means that maybe the perennial ice would not go down as low as last year."