Arctic shrinkage

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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; one study states this might happen before 2015, while a more common theory estimates between 2040 and 2100.^[1] If this event does occur, it would be for the first time in more than 700,000 years.^[2][3][4] Scientists are studying possible cause and effect factors such as unusual wind patterns, rising Arctic temperatures,^[5] or shifting water circulation.^[6]

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."^[7] Reduction of the area of Arctic sea ice means less solar energy is reflected back into space, thus accelerating the reduction.^[8]

Greenland's ice sheet contains enough fresh water as ice to raise sea level worldwide by 7 metres (23 ft).^[8][9] Models predict a sea-level contribution of about 5 centimetres (2 in) from melting in Greenland during the 21st century.^[10] It is also predicted that Greenland will become warm enough by 2100 to begin an almost complete melt during the next 1,000 years or more.^[11][12]

2007 saw a record low in summer sea ice, though most of that iced area reformed during winter; the iced area was almost near normal during the winter of 2007-2008.^[13] However the amount of thick perennial ice was below levels measured in the previous winter.^[14]

As of June 3, 2008, Arctic sea ice is still on track for extreme melting this year according to the NSIDC. Daily ice extents during May have continued to be below the long-term average, approaching the low levels seen at this time last year. The ice is thinner than last year and ice extent is declining more rapidly.^[15]

Contents 1 Dating Arctic ice 2 Recent expert statements 2.1 2007 2.2 2008 3 Research 3.1 National 3.2 International 4 Effects on wildlife 5 Territorial claims 6 References 7 See also 8 Further reading 9 External links

[edit] Dating Arctic ice

Estimates of how long the Arctic Ocean has had perennial ice cover vary.^[4] Those estimates range from 700,000 years in the opinion of Worsley and Herman,^[16] to 4 million years in the opinion of Clark.^[17] Here is how Clark refuted the theory of Worsley and Herman:

Recently, a few coccoliths have been reported from late Pliocene and Pleistocene central Arctic sediment (Worsley and Herman, 1980). Although this is interpreted to indicate episodic ice-free conditions for the central Arctic, the occurrence of ice-rafted debris with the sparse coccoliths is more easily interpreted to represent transportation of coccoliths from ice-free continental seas marginal to the central Arctic. The sediment record as well as theoretical considerations make strong argument against alternating ice-covered and ice-free....The probable Middle Cenozoic development of an ice cover, accompanied by Antarctic ice development and a late shift of the Gulf Stream to its present position, were important events that led to the development of modern climates. The record suggests that altering the present ice cover would have profound effects on future climates.^[17]

More recently, Melnikov has noted that, "There is no common opinion on the age of the Arctic sea ice cover."^[18] Experts apparently agree that the age of the perennial ice cover exceeds 700,000 years but disagree about how much older it is. Overpeck stated in 2005 that it is at least a million years old, and perhaps much older.^[3]

[edit] Recent expert statements

[edit] 2007

Associate professor Carl Egede Bøggild, University Centre in Svalbard was quoted by the New York Times as saying the melting rate of Greenland's ice sheet could be as high as 80 cubic miles per year.^[19] Leif Toudal Pedersen of the Danish National Space Center commented about Arctic sea ice: "The strong reduction in just one year certainly raises flags that the ice (in summer) may disappear much sooner than expected...."^[20] The International Ice Charting Working Group issued a statement that the Arctic sea ice in September 2007 had reached the lowest extent "in the history of ice charting."^[21]

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.^[1]

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.^[1]

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."^[22]

[edit] 2008

In February of 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."^[13]

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.^[14]

According to Meier, NASA satellite data shows that there has been a 50% decrease of perennial Arctic ice between February 2007 and February 2008.^[14]

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.^[23]

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."^[24] From the May 5, 2008 NSIDC report:^[25]

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.

In March 2008, a senior advisor to the Norwegian Ministry of the Environment said that the Arctic polar ice cap could be completely gone during the summer of 2008.^[26][27]

[edit] Research

[edit] National

Individual countries within the Arctic zone, Canada, Denmark (Greenland), Finland, Iceland, Norway, Russia, Sweden, and the United States (Alaska) conduct independent research through a variety of organizations and agencies, public and private, such as Russia's Arctic and Antarctic Research Institute. Countries who do not have Arctic claims, but are close neighbors, conduct Arctic research as well, such as the Chinese Arctic and Antarctic Agency.

[edit] International

International cooperative research between nations has become a priority.

• DAMOCLES (Developing Arctic Modeling and Observing Capabilities for Long-term Environmental Studies): European integrated project "specifically concerned with the potential for a significantly reduced sea ice cover, and the impacts this might have on the environment and on human activities, both regionally and globally".
• European Space Agency (ESA) is scheduled in 2009 to launch CryoSat-2 which will provide satellite data on Arctic ice cover change rates.^[28]
• International Arctic Buoy Program: deploys and maintains buoys that provide real-time position, pressure, temperature, and interpolated ice velocity data
• International Arctic Research Center: Main participants are the United States and Japan.
• International Arctic Science Committee: non-governmental organization (NGO) with diverse membership, including 18 countries from 3 continents.
• 'Role of the Arctic Region', in conjunction with the International Polar Year, was the focus of the second international conference on Global Change Research, held in Nynäshamn, Sweden, October, 2007.^[29][30]
• SEARCH (Study of Environmental Arctic Change): Supported by the Arctic Research Office, a division of the United States' National Oceanic and Atmospheric Administration (NOAA), and the Russian Academy of Sciences.

[edit] Effects on wildlife

In September 2007, the United States Geological Survey completed a year-long study,^[31] 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.^[32] April 3, 2007, the National Wildlife Federation urged the U.S. Congress to place polar bears under the Endangered Species Act.^[33]

[edit] Territorial claims

Main article: Territorial claims in the Arctic

Growing evidence that global warming is shrinking polar ice has added to the urgency of several nations' Arctic territorial claims in hopes of establishing resource development and new shipping lanes, in addition to protecting sovereign rights.^[34]

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.^[35] At the Arctic Ocean Conference, Foreign Ministers and other officials representing the five countries announced the Ilulissat Declaration on May 28, 2008.^[36][37]

[edit] References

[edit] See also

• Arctic Climate Impact Assessment
• Climate of the Arctic

[edit] Further reading

[edit] External links

• Arctic Change website, in near-realtime
• International Arctic Buoy Programme
• International Arctic Research Center
• International Arctic Science Committee
• World Wildlife Foundation's International Arctic Programme
• 38th Annual International Arctic Workshop 2008