The amount of the Arctic Ocean covered by ice at the end of summer by then could be only about 1 million square kilometers, or about 620,000 square miles. That's compared to today's ice extent of 4.6 million square kilometers, or 2.8 million square miles. So much more open water could be a boon for shipping and for extracting minerals and oil from the seabed, but it raises the question of ecosystem upheaval.
While the Intergovernmental Panel on Climate Change in 2007 assessed what might happen in the Arctic in the future based on results from more than a dozen global climate models, two researchers reasoned that dramatic declines in the extent of ice at the end of summer in 2007 and 2008 called for a different approach.
Out of the 23 models now available, the new projections are based on the six most suited for assessing sea ice, according to Muyin Wang, a University of Washington climate scientist with the Joint Institute for the Study of the Atmosphere and Ocean based at the UW, and James Overland, an oceanographer with the National Oceanic and Atmospheric Administration's Pacific Marine Environmental Laboratory in Seattle.
Once the extent of ice at the end of summer drops to 4.6 million square kilometers -- it was actually 4.3 million square kilometers in 2007 and 4.7 million in 2008 -- all six models show rapid sea-ice declines. Averaged together the models point to a nearly ice-free Arctic in 32 years, with some of the models putting the event as early as 11 years from now.
Article continues: http://www.sciencedaily.com/releases/2009/04/090402143752.htm