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.
The sea ice extent for 2008 was greater than that for 2007.
A 2007 study by Professor Wieslaw Maslowski at the U. S. Naval Postgraduate School, Monterey, California predicted that the Arctic Ocean may be free of ice during summer by as soon as 2013. The study used data sets from 1979 to 2004 and did not include the more recent record low ice minima set in 2005 and 2007. Maslowski suggested that other researchers seriously underestimated some key melting processes, producing models that predict an ice free Arctic Ocean to first occur from 2040 to 2100.
Professor Peter Wadhams from University of Cambridge, UK, agreed that some models have not been taking proper account of the physical processes occurring in nature. He said that Maslowski's model is more efficient because it takes account of processes that happen internally in the ice. Wadhams predicted that, in the end, the Arctic ice will just melt away quite suddenly, perhaps not as early as 2013 but much earlier than 2040.
In December 2007, the Canadian Press selected Arctic shrinkage as Canada's biggest environmental story of the year. Environment Canada senior climatologist David Phillips summed it up: "This huge chunk of ice the size of Ontario vanished within one year.
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."
In March 2008, Walt Meier of the National Snow and Ice Data Center (NSIDC) stated:
Thickness is an indicator of long-term health of sea ice, and that's not looking good at the moment. It's like looking at a Hollywood set....It may look OK but if you could see behind you'd see ... it's just empty. And what we're seeing with the ice cover is it's becoming more and more empty underneath the ice cover.
According to Meier, NASA satellite data shows that there has been a 50% decrease of perennial Arctic ice between February 2007 and February 2008.
While the cold winter did allow ice to re-cover much of the Arctic Sea surface area during the Winter of 2007/2008, conditions were far from normal as the pair of NASA images to the right reveals. The February 2008 ice pack contained much more young ice than the long-term average. In the past, more ice survived the summer melt season and had the chance to thicken over the following winter. In the mid- to late 1980s, over 20 percent of Arctic sea ice was at least six years old; in February 2008, just 6 percent of the ice was six years old or older.
In March 2008, NSIDC senior scientist Mark Serreze stated: "We're in for a world of hurt this summer. Depending on the weather, there could be as much melting this year as last, maybe more. From the May 5, 2008 NSIDC report:
Although there is more ice than this time last year, the average decline rate through the month of April was 6,000 square kilometers per day (2,300 thousand square miles per day) faster than last April....An assessment of the available evidence points to another extreme September sea ice minimum. Could the North Pole be ice free this melt season? Given that this region is currently covered with first-year ice, that seems quite possible.
According to Dr. Martin Sommerkorn, an ecosystem ecologist at The Macaulay Institute, and Senior Climate Change Adviser at World Wildlife Federation International's Arctic Programme, "The area of ice that is at least five years old has dramatically fallen by more than half since 1985.
Sea ice loss could cause more rapid warming of Northern latitudes, with effects on permafrost, methane release, and wildlife.
In September 2007, the United States Geological Survey completed a year-long study, which concluded in part that the floating Arctic sea ice will continue its rapid shrinkage over the next 50 years, consequently wiping out much of the polar bears’ habitat. The bears would disappear from Alaska, but would continue to exist in the Arctic archipelago of Canada and areas off the northern Greenland coast. April 3 2007, the National Wildlife Federation urged the U.S. Congress to place polar bears under the Endangered Species Act.
Danish Foreign Minister Per Stig Møller and Greenland's Premier Hans Enoksen invited foreign ministers from Canada, Norway, Russia and the United States to Ilulissat, Greenland for a summit in May 2008 to discuss how to divide borders in the changing Arctic region, and a discussion on more cooperation against climate change affecting the Arctic. At the Arctic Ocean Conference, Foreign Ministers and other officials representing the five countries announced the Ilulissat Declaration on May 28, 2008.