Climate change in the Arctic

From Wikipedia, the free encyclopedia
  (Redirected from Arctic shrinkage)
Jump to: navigation, search
link =
 This article may be expanded with text translated from the corresponding article in the German Wikipedia. (March 2013)
The image above shows where average air temperatures (October 2010–September 2011) were up to 3 degrees Celsius above (red) or below (blue) the long-term average (1981–2010).
The maps above compare the Arctic ice minimum extents from 2012 (top) and 1984 (bottom). In 1984 the sea ice extent was roughly the average of the minimum from 1979 to 2000, and so was a typical year. The minimum sea ice extent in 2012 was roughly half of that average.

Ongoing changes in the climate of the Arctic include rising temperatures, loss of sea ice, and melting of the Greenland ice sheet.[1][2][3] The Arctic ocean will likely be free of summer sea ice before the year 2100. Projections as to when precisely this will occur vary between the years 2060–2080,[4] 2030,[5][6] and 2016.[7][8] Because of the amplified response of the Arctic to global warming, it is often seen as a high-sensitivity indicator of climate change. Scientists also point to the potential for release of methane from the Arctic region, especially through the thawing of permafrost and methane clathrates. Arctic climate changes are summarized in the IPCC Fourth Assessment Report and the Arctic Climate Impact Assessment.

The National Oceanic and Atmospheric Administration (NOAA)'s Arctic Report Card presents annually updated, peer-reviewed information on recent observations of environmental conditions in the Arctic relative to historical records.

Contents

Modelling, history, and predictions of sea ice [edit]

See also: Arctic sea ice ecology and history

Computer models predict that the sea ice area will continue to shrink in the future, although recent work has called into question their ability to accurately predict sea ice changes.[9] Current climate models frequently underestimate the rate of sea ice retreat.[10] In 2007 the IPCC reported that "the projected reduction [in global sea ice cover] is accelerated in the Arctic, where some models project summer sea ice cover to disappear entirely in the high-emission A2 scenario in the latter part of the 21st century.″ [11] There is currently no scientific evidence that a seasonally ice-free Arctic Ocean existed anytime in the last 700,000 years, although there were periods when the Arctic was warmer than it is today.[12][13] 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,[14] rising Arctic temperatures,[15] or shifting water circulation[16] (such as increasing inflows of warm, fresh water to the Arctic Ocean from rivers.)

Sea ice coverage in 1980 (bottom) and 2012 (top), as observed by passive microwave sensors on NASA’s Nimbus-7 satellite and by the Special Sensor Microwave Imager/Sounder (SSMIS) from the Defense Meteorological Satellite Program (DMSP). Multi-year ice is shown in bright white, while average sea ice cover is shown in light blue to milky white. The data shows the ice cover for the period of 1 November through 31 January in their respective years.

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."[17] Reduction of the area of Arctic sea ice means less solar energy is reflected back into space, thus accelerating the reduction.[18] Studies have shown that recent warming in the polar regions was due to the net effect human influence; the warming radiative forcing of greenhouse gases is only partially offset by the cooling effect of ozone depletion.[19] Reliable measurement of sea ice edge begin within the satellite era in the late 1970s. Before this the region was less well monitored by a combination of ships, buoys and aircraft.[20] On top of the long-term negative trend in recent years, attributed to global warming, there is considerable interannual variation.[21] Some of this variation may be related to effects such as the arctic oscillation, which may itself be related to global warming;[22] some of the variation is essentially random "weather noise".

The Arctic sea ice September minimum extent reached new record lows in 2002, 2005, 2007 (39.2 percent below the 1979–2000 average) and 2012. (Roughly 50% below the 1979-2000 average)[23] In 2007, Arctic sea ice broke all previous records by early August—a month before the end of melt season, with the biggest decline ever in Arctic sea ice minimum extent, more than a million square kilometers.[24] In the first time in human memory, the fabled Northwest Passage opened completely.[25] The dramatic 2007 melting surprised and concerned scientists.[26][27]

Seasonal variation and long term decrease of Arctic sea ice volume as determined by measurement backed numerical modelling.[28]
1870–2009 Northern hemisphere sea ice extent in million square kilometers. Blue shading indicates the pre-satellite era; data then is less reliable. In particular, the near-constant level extent in Autumn up to 1940 reflects lack of data rather than a real lack of variation.

From 2008 to 2011, Arctic sea ice minimum extent was higher than 2007, but it did not return to the levels of previous years.[29][30] In 2012 however, the 2007 record low was broken in late August with 3 weeks still left in the melt season.[31] A few days later, as August ended, the sea ice extent dropped below 4 million square kilometers for the very first time on record.[32] It continued to fall, going below 3 and half million square kilometers by mid September, over 600,000 square kilometers lower than the 2007 record low.[33][34] It bottomed out on 16 September 2012 at 3.41 million square kilometers (1.32 million square miles), or 760,000 square kilometers (293,000 square miles) below the previous low set on 18 September 2007.[32]

The sea ice thickness field, and accordingly the ice volume and mass, is much more difficult to determine than the extension. Exact measurements can be made only at a limited number of points. Because of large variations in ice and snow thickness and consistency air- and spaceborne-measurements have to be evaluated carefully. Nevertheless the studies made support the assumption of a dramatic decline in ice age and thickness.[30] The Catlin Arctic Survey reported an average thickness of 1.8 meters across the northern Beaufort Sea, an area that had traditionally contained older, thicker ice.[35] Another approach[28] is to simulate ice growth, melting and drift numerically in an integrated ocean-atmosphere model with input parameters fine tuned to fit model output to known thickness and extent data.

The rate of the decline in entire arctic ice coverage is accelerating. From 1979–1996, the average per decade decline in entire ice coverage was a 2.2% decline in ice extent (i.e., area with at least 15% sea ice coverage) and a 3% decline in ice area. For the decade ending 2008, these values have risen to 10.1% and 10.7%, respectively. These are comparable to the September to September loss rates in year-round ice (i.e., perennial ice, which survives throughout the year), which averaged a retreat of 10.2% and 11.4% per decade, respectively, for the period 1979–2007.[36] This is consistent with ICESat measurements indicating decreased thickness in arctic ice and a decline in multi-year ice. For the period 2005–2008, multi-year ice decreased 42% in coverage and 40% in volume, a loss of ~6300 km3.[37] While the arctic ice coverage showed an accelerating downward trend, recent reports on the arctic ice volume showed an even sharper decline then the ice coverage. Since 1979, the ice volume has shrunk by 80% and in just the past decade the volume declined by 36% in the autumn and 9% in the winter.[38]

A 2010 study attributes that the recent Arctic temperature amplification was caused by the loss of sea ice itself, which exposes water instead of more reflective ice to solar radiation.[39]

A study published in 2013 shows simply extending summertime ice melting trends into the future in a straight line predicts an ice-free summertime Arctic as early as by 2020.[40][41]

Effects [edit]

Earlier retreat of sea ice in Barrow, Alaska

The effects of Arctic climate change include a marked decrease in Arctic sea ice; thawing permafrost, leading to the release of methane, a potent greenhouse gas;[42] the release of methane from clathrates, leading to longer time-scale methane release;[43] the observed increase in melt on the Greenland Ice Sheet in recent years; and potential changes in patterns of ocean circulation. Scientists worry that some of these effects may cause positive feedbacks which could accelerate the rate of global warming.

Sea ice [edit]

The number of days where the arctic is in the melt stage has increased since satellite records began in 1979. Red indicates more melting, blue less melting.

The sea ice in the Arctic region is in itself important in maintaining global climate due to its albedo (reflectivity).[44] Melting of this sea ice will therefore exacerbate global warming due to positive feedback effects, where warming creates more warming by increased solar absorption.[44][45] An important feedback in the Arctic currently is ice-albedo feedback. The loss of the Arctic sea ice may represent a tipping point in global warming, when 'runaway' climate change starts.[46][47] This would be due to the release of methane from permafrost and clathrates in the region, and also because of ice-albedo feedback effects. However, recent research has challenged the notion of ice-albedo feedback causing an imminent Arctic sea ice tipping point.[48][49] Other scientists though believe that the Arctic has already passed the tipping point. Professor Peter Wadhams told the Guardian in September 2012 after the Arctic sea ice extent hit a record low that he predicts the Arctic will be ice free within the next four years.[50]

The reduction of sea ice has also boosted the productivity of phytoplankton by about twenty percent over the past thirty years. However, the effect on marine ecosystems is unclear, since the larger types of phytoplankton, which are the preferred food source of most marine animals, do not appear to have increased as much as the smaller types. So far, arctic phytoplankton have not had a significant impact on the global carbon cycle.[51] In summer, the melt ponds on young and thin ice have allowed sunlight to penetrate the ice, in turn allowing phytoplankton to bloom in unexpected concentrations, although it is unknown just how long this phenomenon has been occurring.[52]

Projected change in polar bear habitat from 2001–2010 to 2041–2050

3 April 2007, the National Wildlife Federation urged the United States Congress to place polar bears under the Endangered Species Act.[53] Four months later, the United States Geological Survey completed a year-long study[54] 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 Canadian Arctic Archipelago and areas off the northern Greenland coast.[55] Secondary 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.

Loss of permafrost [edit]

Main article: Arctic methane release

Sea ice loss has melting effects on permafrost,[56] both in the sea,[57] and on land[58] and consequential effects on methane release, and wildlife.[58] 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.[58] This thawing of the permafrost might accelerate methane release from areas like Siberia.[59] When the temperature warms sufficiently to cause the deep layers of ice underground (the permafrost) to melt, ground water will start seeping into the underlying strata and aquifer and thereby reduce the level of moisture. It may also become farmland after it is drained by canals as was done in the northern American Midwest region so wheat and corn could be farmed in what was previously swampland.[60]

Changes in vegetation [edit]

Western Hemisphere Arctic Vegetation Index Trend
Eastern Hemisphere Vegetation Index Trend

Over the past three decades, temperatures have risen faster in the Arctic than anywhere else in the world. Consequently, the growing season has gotten longer in the far northern latitudes, bringing major changes to plant communities in tundra and boreal (also known as taiga) ecosystems.

For decades, instruments on various NASA and NOAA satellites have continuously monitored vegetation from space. The Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Very High Resolution Radiometer (AVHRR) instruments measure the intensity of visible and near-infrared light reflecting off of plant leaves. Scientists use that information to calculate the Normalized Difference Vegetation Index (NDVI), an indicator of photosynthetic activity or “greenness” of the landscape.

The maps above show NDVI trends between July 1982 and December 2011 for the northern portions of North America and Eurasia. Shades of green depict areas where plant productivity and abundance increased; shades of brown show where photosynthetic activity declined. There was no significant trend in areas that are white, and areas that are gray were not included in the study. An international team of university and NASA scientists published their analysis of the NDVI data in Nature Climate Change in March 2013.

The maps show a ring of greening in the treeless tundra ecosystems of the circumpolar Arctic—the northernmost parts of Canada, Russia, and Scandinavia. Tall shrubs and trees started to grow in areas that were previously dominated by tundra grasses. The researchers concluded that plant growth had increased by 7 to 10 percent overall.

However, boreal forests, particularly those in North America, showed a different response to warming. Many boreal forests greened, but the trend was not as strong as it was for tundra of the circumpolar Arctic. In North America, some boreal forests actually experienced “browning” (less photosynthetic activity) over the study period. Droughts, forest fire activity, animal and insect behavior, industrial pollution, and a number of other factors may have contributed to the browning.

“Satellite data identify areas in the boreal zone that are warmer and drier and other areas that are warmer and wetter,” explained co-author Ramakrishna Nemani of NASA’s Ames Research Center. “Only the warmer and wetter areas support more growth.”

“We found more plant growth in the boreal zone from 1982 to 1992 than from 1992 to 2011, because water limitations were encountered in the later two decades of our study,” added co-author Sangram Ganguly of the Bay Area Environmental Research Institute and NASA Ames. [61]

The less severe winters in tundra areas allow shrubs such as alders to replace moss and lichens. The feedback effect of shrubs on the tundra's permafrost is unclear, however. In the winter they trap more snow which insulates the permafrost from extreme cold spells, but in the summer they shade the ground from direct sunlight.[62]

Clathrate gun [edit]

Main article: Clathrate gun hypothesis

Sea ice serves to stabilise methane deposits on and near the shoreline,[63] preventing the clathrate breaking down and outgassing methane into the atmosphere. Any methane released to the atmosphere will then cause further warming.[42]

Melting of the Greenland Ice Sheet [edit]

Albedo Change on Greenland
Greenland Ice Sheet Mass Trend[when?]

Models predict a sea-level contribution of about 5 centimetres (2 in) from melting in Greenland during the 21st century.[64] 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.[65][66] In early July 2012, 97% percent of the Ice Sheet experienced some form of surface melt including the summits.[67]

Ice thickness measurements from the GRACE satellite indicate that ice mass loss is accelerating. For the period 2002–2009, the rate of loss increased from −137 Gt/yr to −286 Gt/yr, with an acceleration of −30 gigatonnes per year per year.[68]

Effect on ocean circulation [edit]

See also: Shutdown of thermohaline circulation and Ocean anoxic event

Although this is now thought unlikely in the near future, it has also been suggested that there could be a shutdown of thermohaline circulation, similar to that which is believed to have driven the Younger Dryas, an abrupt climate change event. There is also potentially a possibility of a more general disruption of ocean circulation, which may lead to an ocean anoxic event, although these are believed to be much more common in the distant past. It is unclear whether the appropriate pre-conditions for such an event exist today.

Control of Arctic climate change [edit]

Geoengineering [edit]

See also: Arctic geoengineering and Geoengineering

Geoengineering approaches offer interventions which may increase Arctic ice, or reduce its decline.[69] These operate either by regional effects (Arctic geoengineering) or global effects (geoengineering). Several specific Arctic geoengineering schemes have been proposed to reduce Arctic climate change. Further, scientists such as Paul Crutzen have argued for general geoengineering proposals such as using stratospheric sulfur aerosols to be used, which will affect the Arctic if deployed in or near this region.

According to John Holdren, Assistant to the President of the United States for Science and Technology, complete loss of summer sea ice in the Arctic would be a milestone that could justify geoengineering in order to purposely cool the climate. Holdren believes that complete loss of summer sea ice in the Arctic could signal an increased chance of "really intolerable consequences."[70]

Research [edit]

National [edit]

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 Administration (CAA).

International [edit]

International cooperative research between nations has become increasingly important:

Territorial claims [edit]

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.[74]

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.[75] At the Arctic Ocean Conference, Foreign Ministers and other officials representing the five countries announced the Ilulissat Declaration on 28 May 2008.[76][77]

Social Impacts [edit]

Many of the causes of climate change in the Arctic can be attributed to the effect that humans have had on the atmosphere, greenhouse effect is mainly caused by the increase in CO2 levels created by people.[78] Climate change is having a direct impact on the people that live in the Arctic, as well as other societies around the world.[79] People are affecting the geographic space of the Arctic and the Arctic is affecting people.

The warming environment presents challenges to local communities such as the Inuit. Hunting, which is a major way of survival for some small communities, will be changed with increasing temperatures.[80] The reduction of sea ice will cause certain species populations to decline or even become extinct.[79] In good years, some communities are fully employed by the commercial harvest of certain animals.[80] The harvest of different animals fluctuates each year and with the rise of temperatures it is likely to continue changing and creating issues for Inuit hunters. Unsuspected changes in river and snow conditions will cause herds of animals, including reindeer, to change migration patterns, calving grounds, and forage availability.[79]

Governments and business entrepreneurs are attempting to benefit from the melting sea ice.[81] Major shipping lanes are opening up, the northern sea route route had 34 passages in 2011 while the Northwest Passage had 22 traverses, this is more than ever in history.[82] These sea routes could see a lot of economic benefits for those involved.[82] Shipping companies are likely to benefit from the shortened distance of these northern routes. Access to natural resources will increase, including valuable minerals and offshore oil and gas.[79] This will likely bring new interestest to those directly involved. At first, it is likely that finding and controlling these resources will be difficult with the continual moving ice.[79] Expansion of tourism is probable in the arctic as sea ice reduces. With less ice, exploration and sight seeing in the Arctic will become continuously safer and popular.[79]

Transportation in the Arctic is already beginning to struggle. Some transportation routes and pipelines on land are being disrupted by the melting of ice.[79] Many Arctic communities rely on frozen roadways to transport supplies and travel from area to area.[79] The changing landscape and unpredictability of weather is creating challenges that were non-existent previously in the Arctic.[83] The adaptation to the continual changing in the environment will be a challenge. The relationship between people, communities, and institutions is important when trying to understand adaptations processes.[83]

See also [edit]

Portal icon Global warming portal
Portal icon Ecology portal
Portal icon Environment portal

References [edit]

  1. ^ Foster, Joanna M. (2012-02-08). "From 2 Satellites, the Big Picture on Ice Melt". The New York Times. 
  2. ^ Slivka K (2012-07-25). "Rare Burst of Melting Seen in Greenland Ice Sheet". NYTimes.com. Retrieved 2012-11-04. 
  3. ^ Goldenberg S (2012-07-24). "Greenland ice sheet melted at unprecedented rate during July | Environment |". The Guardian. Retrieved 2012-11-04. 
  4. ^ Boé, J.; Hall, A.; Qu, X. (2009). "September sea-ice cover in the Arctic Ocean projected to vanish by 2100". Nature Geoscience 2 (5): 341. Bibcode:2009NatGe...2..341B. doi:10.1038/ngeo467.  edit
  5. ^ Roach, John (2009-10-15). "Arctic Largely Ice Free in Summer Within Ten Years?". National Geographic News. Retrieved 2010-10-02. 
  6. ^ Richard A. Kerr (28 September 2012). "Ice-Free Arctic Sea May be Years, Not Decades, Away". Science 337: 1591. 
  7. ^ Arctic Sea Ice May Disappear Within 4 Years, According To One Of The World’s Leading Sea Ice Researchers
  8. ^ Amos, Jonathan (2011-04-08). "New warning on Arctic sea ice melt". BBC News Online. 
  9. ^ Eisenman, Ian; Untersteiner, Norbert; Wettlaufer, J.S. (2007). "On the reliability of simulated Arctic sea ice in Global Climate Models". Geophysical Research Letters 34 (10): L10501. Bibcode:2007GeoRL..3410501E. doi:10.1029/2007GL029914.  This is due to high sea ice thickness sensitivity to variations in downward thermal radiation, which are not reflected in outcomes of different models but seem to have been compensated by adaption of other parameters like albedo, short wave irradiation or ocean heat flux.
  10. ^ Stroeve, J.; Holland, M. M.; Meier, W.; Scambos, T.; Serreze, M. (2007). "Arctic sea ice decline: Faster than forecast". Geophysical Research Letters 34 (9): L09501. Bibcode:2007GeoRL..3409501S. doi:10.1029/2007GL029703.  edit
  11. ^ Meehl, G.A., and others; Intergovernmental Panel on Climate Change Working Group I. (2007). Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Chapter 10. New York: Cambridge University Press. 
  12. ^ Overpeck, Jonathan T.; Sturm, Matthew; Francis, Jennifer A.; Perovich, Donald K.; Serreze, Mark C.; Benner, Ronald; Carmack, Eddy C.; Chapin, F. Stuart et al. (2005-08-23). "Arctic System on Trajectory to New, Seasonally Ice-Free State" (PDF). Eos, Transactions, American Geophysical Union 86 (34): 309–316. Bibcode:2005EOSTr..86..309O. doi:10.1029/2005EO340001. Retrieved 2007-12-24. 
  13. ^ Butt, F. A.; H. Drange, A. Elverhoi, O. H. Ottera & A. Solheim (2002). The Sensitivity of the North Atlantic Arctic Climate System to Isostatic Elevation Changes, Freshwater and Solar Forcings 21 (14–15). Quaternary Science Reviews. pp. 1643–1660. OCLC 108566094. 
  14. ^ "Winds from Siberia reduce Arctic sea ice cover". The Research Council of Norway. 2010-04-27. Retrieved 2010-04-27. 
  15. ^ Black, Richard (2006-09-14). "'Drastic' shrinkage in Arctic ice". Science/Nature (BBC News). Retrieved 2007-09-16. 
  16. ^ "Study: Circulation Shift May Be Melting Arctic Sea Ice". Fox News. 2007-11-24. Retrieved 2007-11-27. 
  17. ^ McCarthy, James J.; Intergovernmental Panel on Climate Change Working Group II. (2001). Climate Change 2001: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Third Assessment Report of the Intergovernmental Panel on Climate Change. New York: Cambridge University Press. ISBN 0-521-80768-9. Retrieved 2007-12-24. 
  18. ^ Black, Richard (2007-05-18). "Earth – melting in the heat?". BBC News. Retrieved 2008-01-03. 
  19. ^ Gillett, N. P.; Stone, D. I. A.; Stott, P. A.; Nozawa, T.; Karpechko, A. Y.; Hegerl, G. C.; Wehner, M. F.; Jones, P. D. (2008). "Attribution of polar warming to human influence". Nature Geoscience 1 (11): 750. doi:10.1038/ngeo338.  edit
  20. ^ Meier, W.N.; J.C. Stroeve, and F. Fetterer (2007). "Whither Arctic sea ice? A clear signal of decline regionally, seasonally and extending beyond the satellite record". Annals of Glaciology 46: 428–434. Bibcode:2007AnGla..46..428M. doi:10.3189/172756407782871170. 
  21. ^ "NASA Sees Arctic Ocean Circulation Do an About-Face". JPL News (Pasadena: JPL/California Institute of Technology). 2007-11-13. Retrieved 2010-07-26. 
  22. ^ Fyfe, J.C; G.J. Boer and G.M. Flato (1999-06-01). "The Arctic and Antarctic Oscillations and their Projected Changes Under Global Warming". Geophysical Research Letters 26 (11): 1601–4. Bibcode:1999GeoRL..26.1601F. doi:10.1029/1999GL900317. 
  23. ^ http://www.metoffice.gov.uk/news/releases/archive/2012/sea-ice-minimum
  24. ^ "State of the Cryosphere, Is the Cryosphere sending signals about climate change?". National Snow and Ice Data Center. 2010-02-18. Retrieved 2010-07-26. 
  25. ^ "NSIDC Arctic Sea Ice News Fall 2007". Retrieved 2012-11-04. 
  26. ^ Cole, Stephen (2007-09-25). "'Remarkable' Drop in Arctic Sea Ice Raises Questions". NASA. Retrieved 2010-07-26. 
  27. ^ "Monitoring Sea Ice". NASA Earth Observatory. NASA. 2010-07-25. Retrieved 2010-07-26. 
  28. ^ a b Zhang, Jinlun and D.A. Rothrock (2003). "Modeling global sea ice with a thickness and enthalpy distribution model in generalized curvilinear coordinates". Mon. Wea. Rev. 131 (5): 681–697. 
  29. ^ "Summer 2011: Arctic sea ice near record lows | Arctic Sea Ice News and Analysis". Retrieved 2012-11-04. 
  30. ^ a b "Arctic sea ice extent remains low; 2009 sees third-lowest mark". NSIDC. 2009-10-06. Retrieved 2010-07-26. 
  31. ^ "Arctic sea ice extent breaks 2007 record low | Arctic Sea Ice News and Analysis". Retrieved 2012-11-04. 
  32. ^ a b "Arctic Sea Ice News and Analysis | Sea ice data updated daily with one-day lag". Retrieved 2012-11-04. 
  33. ^ "Arctic Sea Ice Extent". Retrieved 2012-11-04. 
  34. ^ http://www.smh.com.au/environment/climate-change/staggering-arctic-ice-loss-smashes-melt-records-20120917-260zu.html
  35. ^ "Sea Ice Loss (2009) | Catlin Arctic Survey". Retrieved 2012-11-04. 
  36. ^ Comiso, Josefino C.; Parkinson, Claire L.; Gersten, Robert; Stock, Larry (2008). "Accelerated decline in Arctic sea ice cover". Geophysical Research Letters 35: L01703. Bibcode:2008GeoRL..3501703C. doi:10.1029/2007GL031972. 
  37. ^ Kwok, R.; Cunningham, G.F.; Wensnahan, M.; Rigor, I.; Zwally, H.J.; Yi D. (2009). "Thinning and volume loss of Arctic sea ice: 2003–2008". Journal of Geophysical Research 114: C07005. Bibcode:2009JGRC..11407005K. doi:10.1029/2009JC005312. 
  38. ^ http://www.wunderground.com/blog/JeffMasters/article.html?entrynum=2352
  39. ^ Screen, J. A.; Simmonds, I. (2010). "The central role of diminishing sea ice in recent Arctic temperature amplification". Nature 464 (7293): 1334–1337. Bibcode:2010Natur.464.1334S. doi:10.1038/nature09051. PMID 20428168.  edit
  40. ^ doi:10.1002/grl.50316
  41. ^ Arctic summers may be ice free sooner than predicted April 12, 2013 USA Today
  42. ^ a b Christensen, T. R.; Johansson, T. Ö.; Jonas Åkerman, H.; Mastepanov, M.; Malmer, N.; Friborg, T.; Crill, P.; Svensson, B. H. (2004). "Thawing sub-arctic permafrost: Effects on vegetation and methane emissions". Geophysical Research Letters 31 (4): L04501. Bibcode:2004GeoRL..3104501C. doi:10.1029/2003GL018680.  edit
  43. ^ Macdonald, G. J. (1990). "Role of methane clathrates in past and future climates". Climatic Change 16 (3): 247–243. doi:10.1007/BF00144504.  edit
  44. ^ a b "All About Sea Ice". NSIDC. Retrieved 2009-01-10. 
  45. ^ "Global Outlook for Ice and Snow, Chapter 5: Ice in the Sea". United Nations Environment Programme. pp. 75–76. 
  46. ^ Lawrence, D. M.; Slater, A. (2005). "A projection of severe near-surface permafrost degradation during the 21st century". Geophysical Research Letters 32 (24): L24401. Bibcode:2005GeoRL..3224401L. doi:10.1029/2005GL025080.  edit
  47. ^ Archer, D.; Bufett, B. (2005). "Time-dependent response of the global ocean clathrate reservoir to climatic and anthropogenic forcing". Geochemistry Geophysics Geosystems 6 (3): Q03002. Bibcode:2005GGG.....603002A. doi:10.1029/2004GC000854.  edit
  48. ^ "Arctic summer sea ice loss may not 'tip' over the edge". environmentalresearchweb. 2009-01-30. Retrieved 2010-07-26. 
  49. ^ Eisenman, Ian; Wettlaufer, J.S. (2009). "Nonlinear threshold behavior during the loss of Arctic sea ice". Proceedings of the National Academy of Sciences of the United States of America 106 (1): 28–32. arXiv:0812.4777. Bibcode:2009PNAS..106...28E. doi:10.1073/pnas.0806887106. PMC 2629232. PMID 19109440. 
  50. ^ http://www.guardian.co.uk/environment/2012/sep/17/arctic-collapse-sea-ice
  51. ^ Kennedy, Caitlyn (1 December 2011). "Sea Ice Declines Boost Arctic Phytoplankton Productivity". ClimateWatch Magazine. NOAA. Retrieved 20 January 2012. 
  52. ^ "Unprecedented Blooms of Ocean Plant Life". NASA Science News. 8 June 2012. Retrieved 12 June 2012. 
  53. ^ "Protection For Polar Bears Urged By National Wildlife Federation". Science Daily. 2008-04-03. Retrieved 2008-04-03. 
  54. ^ DeWeaver, Eric; U.S. Geological Survey (2007). "Uncertainty in Climate Model Projections of Arctic Sea Ice Decline: An Evaluation Relevant to Polar Bears" (PDF). United States Department of the Interior. OCLC 183412441. 
  55. ^ Broder, John; Revkin, Andrew C. (2007-07-08). "Warming Is Seen as Wiping Out Most Polar Bears". The New York Times. Retrieved 2007-09-23. 
  56. ^ "Microsoft Word - lawrence.grl.submit.doc" (PDF). Retrieved 2010-07-26. 
  57. ^ Stranahan, Susan Q. "Melting Arctic Ocean Raises Threat of ‘Methane Time Bomb’". E360.yale.edu. Retrieved 2010-07-26. 
  58. ^ a b c "Permafrost Threatened by Rapid Retreat of Arctic Sea Ice, NCAR Study Finds – News Release". Ucar.edu. Retrieved 2010-07-26. 
  59. ^ "Methane Bubbling Up From Undersea Permafrost?". News.nationalgeographic.com. Retrieved 2010-07-26. 
  60. ^ "Technical Aspects of Wetlands - History of Wetlands in the Conterminous United States". U.S. Geological Survey-. Retrieved 2012-05-09. 
  61. ^ "The Greening Arctic, NASA Image of the Day". Retrieved 2013-03-16. 
  62. ^ Lindsey, Rebecca (18 January 2012). "Shrub Takeover One Sign of Arctic Change". ClimateWatch Magazine. NOAA. Retrieved 19 January 2012. 
  63. ^ Shakhova, N.; Semiletov, I.; Panteleev, G. (2005). "The distribution of methane on the Siberian Arctic shelves: Implications for the marine methane cycle". Geophysical Research Letters 32 (9): L09601. Bibcode:2005GeoRL..3209601S. doi:10.1029/2005GL022751.  edit
  64. ^ IPCC AR4 chapter 10 [1] Table 10.7
  65. ^ Gregory JM; Huybrechts P; Raper SC (April 2004). "Climatology: threatened loss of the Greenland ice-sheet". Nature 428 (6983): 616. Bibcode:2004Natur.428..616G. doi:10.1038/428616a. PMID 15071587. "The Greenland ice-sheet would melt faster in a warmer climate and is likely to be eliminated — except for residual glaciers in the mountains — if the annual average temperature in Greenland increases by more than about 3 °C. This would raise the global average sea-level by 7 metres over a period of 1000 years or more. We show here that concentrations of greenhouse gasses will probably have reached levels before the year 2100 that are sufficient to raise the temperature past this warming threshold." 
  66. ^ "Regional Sea Level Change" (Figure 11.16). Intergovernmental Panel on Climate Change. 
  67. ^ "NASA - Satellites See Unprecedented Greenland Ice Sheet Surface Melt". Retrieved 2012-11-04. 
  68. ^ Velicogna, I. (2009). "Increasing rates of ice mass loss from the Greenland and Antarctic ice sheets revealed by GRACE". Geophysical Research Letters 36: L19503. Bibcode:2009GeoRL..3619503V. doi:10.1029/2009GL040222. 
  69. ^ Lenton, T; N. Vaughan. "Geoengineering: a critical review". Retrieved 2009-02-23. 
  70. ^ Borenstein, Seth. "Obama Looking at Cooling Air to Fight Warming", Associated Press via ABC News. (2009-04-09).
  71. ^ "ESA's ice mission CryoSat-2". esa.int. 2008-09-11. Retrieved 2009-06-15. 
  72. ^ Svenningsson, Annakarin (2007-10-14). "Global Environmental Change – The Role of the Arctic Region". innovations-report.de. Retrieved 2007-10-16. 
  73. ^ Wininger, Corinne (2007-10-26). "E SF, VR, FORMAS sign MOU to promote Global Environmental Change Research". innovations-report.de. Retrieved 2007-11-26. 
  74. ^ Eckel, Mike (2007-09-20). "Russia: Tests Show Arctic Ridge Is Ours". The Washington Post. Associated Press. Retrieved 2007-09-21. [dead link]
  75. ^ "Denmark aims for meeting of Arctic nations to discuss borders" (online). Denmark-Diplomacy (EUX.TV the Europe channel). 2007-09-13. Archived from the original on 2008-02-29. Retrieved 2007-09-16. 
  76. ^ "Conference in Ilulissat, Greenland: Landmark political declaration on the future of the Arctic". Ministry of Foreign Affairs of Denmark. 2008-05-28. Archived from the original on 2008-06-15. Retrieved 2008-06-06. 
  77. ^ "The Ilulissat Declaration". Ministry of Foreign Affairs (Denmark). 2008-05-28. Retrieved 2008-06-06. 
  78. ^ "Greenhouse Effect". Retrieved 2012-11-04. 
  79. ^ a b c d e f g h Hassol], Arctic Climate Impact Assessment ; author, Susan Joy (2004). Impacts of a warming Arctic (Reprinted. ed.). Cambridge, U.K.: Cambridge University Press. ISBN 978-0-521-61778-9. 
  80. ^ a b Berkes F, Jolly D (2001). "Adapting to Climate Change: Social-Ecological Resilience in a Canadian Western Arctic Community". Conservation Ecology (pdf) 5 (2): 18.  Unknown parameter |ur= ignored (help);
  81. ^ As The Earth Warms, The Lure Of The Arctic's Natural Resources Grows; Under the thawing Arctic ice lies bounty that could fill mouths, and pockets, around the world 02.01.2013 Popular Science
  82. ^ a b "Melting Arctic brings new opportunities - Opinion - Al Jazeera English". Retrieved 2012-11-04. 
  83. ^ a b Nuttall, Mark; Pierre-André Forest, Svein. D. Mathiesen (February 2008). "Adaptation to Climate Change in The Arctic". University of the Arctic: 1–5. Retrieved 2012-11-05. 

Further reading [edit]

External links [edit]

Retrieved from "http://en.wikipedia.org/w/index.php?title=Climate_change_in_the_Arctic&oldid=552175265"