Arctic shrinkage edit
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Arctic shrinkage edit
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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. Whilst there is a periodic variation in ice extent due to the Arctic oscillation, among other varying factors,1 there is a long-term shrinkage trend. (It is notable that the Arctic oscillation itself is believed to be affected strongly by global warming.)
The current Arctic climate was created in the Azolla event, when huge quantities of carbon dioxide was removed from the atmosphere and stored in the Arctic region, in forms which include oil and natural gas. The resulting reduction in the greenhouse effect caused the modern global climate, with permanent Arctic ice cover. Global warming threatens to reverse this process, and strong evidence suggests that this trend is well advanced.
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, although one estimate places it as soon as 2013.2 Scientific analysis currently has no evidence of seasonally ice-free Arctic for more than 700,000 years prior to today's date, although there were warmer periods.34 Some previous predictions suggested 2008 as the earliest ice-free year at the actual pole5 Scientists are studying possible causal factors such as direct changes resulting from the greenhouse effect as well as indirect changes such as unusual wind patterns, rising Arctic temperatures,6 or shifting water circulation7 (such as increasing inflows of warm, fresh water to the Arctic ocean from rivers.)
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."8 Reduction of the area of Arctic sea ice means less solar energy is reflected back into space, thus accelerating the reduction.9
2007 saw a record low in summer sea ice. Some of the newly melted area refroze, increasing the ice area by about 10% by summer 2008.1011 The volume of sea ice, as opposed to the area, remains on a downward trend. Particularly notable was that the amount of thick perennial ice was below levels measured in the previous winter.12.
It should be noted that the volume of ice is much more significant an indication of global warming than is the area, which can change relatively quickly. However, the area covered at a particular point is what determines the albedo of the Arctic region and thus has an important effect on future warming (or cooling) trends. Assessing sea ice extent is prone to errors of method and interpretation, as can be seen from Steven Goddard's public volte-face on the issue.13
The loss of the Arctic sea ice may represent a tipping point in global warming, when further warming becomes rapid and unstoppable.14 This is due to the release of methane from permafrost and clathrates in the region, and also because of albedo effects.
Some commentators have suggested Arctic geoengineering to keep the sea ice intact. Should the tipping point be reached, reduction of greenhouse gas emissions will no longer be sufficient to control global warming, and then geoengineering would be the only option left to avoid catastrophic climate change.
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The thawing of the Arctic affects not only sea ice but has global effects. As well as the Arctic's geological stores of carbon in the form of sedimentary rocks and fossil fuels, vast quantities of carbon exist in the form of methane stored in permafrost and clathrates. A loss of this ice cover is expected to cause the re-release of this stored methane back into the atmosphere. While the carbon locked up in this methane was absorbed from the atmosphere in the form of CO2, it will be re-released largely as gaseous methane, which is a potent greenhouse gas. As a result, should even a small proportion of the stored carbon in permafrost and clathrates be released, the global warming effects may be very severe.
The sea ice in the Arctic region is in itself important in maintaining global climate due to its albedo (reflectivity).citation needed Melting of this sea ice will therefore exacerbate global warming due to positive feedback effects, where warming creates more warming by increased solar absorbtion.
April 3, 2007, the National Wildlife Federation urged the U.S. Congress to place polar bears under the Endangered Species Act.15 Four months later, the United States Geological Survey completed a year-long study16 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 bear 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.17 Seondary ecological effects are also resultant from the shrinkage of sea ice; for example, Polar Bears are denied their historic length of seal hunting season due to late formation and early thaw of pack ice.
Sea ice loss has melting effects on permafrost18, both in the sea19, and on land20 and consequential effects on methane release, and wildlife.21 Some studies imply a direct link, as they predict cold air passing over ice is replaced by warm air passing over the sea. This warm air carries heat to the permafrost around the Arctic, and melts it.22 This permafrost then releases huge quantities of methane.23
Sea ice serves to stabilise methane deposits on and near the shoreline,24 preventing the clathrate breaking down and outgassing methane into the atmosphere, causing further warming. Melting of this ice may release large quantities of methane, a powerful greenhouse gas into the atmosphere, causing further warming in a dangerous positive feedback cycle.25
The sea ice acts as an effective thermal insulator, keeping the heat of the ocean stored and preventing it reaching the atmosphere. Temperature differences of 40C are common between the ocean and the air. The resulting cold air is an important driver of winter weather systems around the Northern hemisphere.citation needed Reduced summer ice extents will affect weather patterns significantly, notably so in the early winter, regardless of any surface freezing that may occur in the mid to late winter.fact
Greenland's ice sheet contains enough fresh water as ice to raise sea level worldwide by 7 metres (23 ft).926 Models predict a sea-level contribution of about 5 centimetres (2 in) from melting in Greenland during the 21st century.27 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.2829 It is viewed by some scientists that wholly inadequate attention is being given to this issue,30, which threatens to displace a significant proportion of the World's population by submerging coastal communities.
It is possible that even with aggressive and speedy reductions in greenhouse gas emissions, Arctic thawing cannot be stopped, due to pre-existing warming effects from historically-emitted greenhouse gases.citation needed According to the most ambitious of IEA emissions scenarios,31 cutting global CO2-equivalent emissions by 50 percent by 2050 is possible. However ambitious, this will only lead to a further rise in CO2 concentrations and temperatures, compared to 2008 values. Concluding from that present mitigation efforts will not be able to prevent continued Arctic melting.
Geoengineering approaches offer an opportunity to prevent the total loss of Arctic ice, either by regional effects (Arctic geoengineering) or global effects (geoengineering). For example, in September 200832 building the St. Lawrence Dam was proposed, a plan to influence temperature and salinity in the Arctic Ocean, favouring sea ice conditions.
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.33
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...."34 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."35
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 2100.2
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 2040.2
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."36
According to Walt Meier of the National Snow and Ice Data Center (NSIDC), NASA satellite data shows that there has been a 50% decrease of perennial Arctic ice between February 2007 and February 2008.12
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, and the total volume was arguably the lowest on record. 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.38
NSIDC says
Arctic sea ice extent during the 2008 melt season dropped to the second-lowest level since satellite measurements began in 1979, reaching the lowest point in its annual cycle of melt and growth on September 14, 2008. Average sea ice extent over the month of September... was 4.67 million square kilometers... The record monthly low, set in 2007, was 4.28 million square kilometers... the now-third-lowest monthly value, set in 2005, was 5.57 million square kilometers... The 2008 season strongly reinforces the thirty-year downward trend in Arctic ice extent. The 2008 September low was 34% below the long-term average from 1979 to 2000 and only 9% greater than the 2007 record... Because the 2008 low was so far below the September average, the negative trend in September extent has been pulled downward, from –10.7 % per decade to –11.7 % per decade. [2]
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.
International cooperative research between nations has become increasingly important:
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.42
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.43 At the Arctic Ocean Conference, Foreign Ministers and other officials representing the five countries announced the Ilulissat Declaration on May 28, 2008.4445
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