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Regional effects of climate change

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Regional effects of global warming are long-term significant changes in the expected patterns of average weather of a specific region due to global warming. The world average temperature is rising due to the greenhouse effect caused by increasing levels of greenhouse gases, especially carbon dioxide. When the global temperature changes, the changes in climate are not expected to be uniform across the Earth. In particular, land areas change more quickly than oceans, and northern high latitudes change more quickly than the tropics, and the margins of biome regions change faster than do their cores.

Regional effects of global warming vary in nature. Some are the result of a generalised global change, such as rising temperature, resulting in local effects, such as melting ice. In other cases, a change may be related to a change in a particular ocean current or weather system. In such cases, the regional effect may be disproportionate and will not necessarily follow the global trend.

There are three major ways in which global warming will make changes to regional climate: melting or forming ice, changing the hydrological cycle (of evaporation and precipitation) and changing currents in the oceans and air flows in the atmosphere. The coast can also be considered a region, and will suffer severe impacts from sea level rise.

Especially affected regions

The Arctic, Africa, small islands and Asian megadeltas are regions that are likely to be especially affected by future climate change.[1] Within other areas, some people are particularly at risk from future climate change, such as the poor, young children and the elderly.[1]

The Arctic is likely to be especially affected by climate change because of the high projected rate of regional warming and associated impacts.[1] Temperature projections for the Arctic region were assessed by Anisimov et al. (2007).[2] These suggested areally averaged warming of about 2 °C to 9 °C by the year 2100. The range reflects different projections made by different climate models, run with different forcing scenarios. Radiative forcing is a measure of the effect of natural and human activities on the climate. Different forcing scenarios reflect, for example, different projections of future human greenhouse gas emissions.

Africa is likely to be the continent most vulnerable to climate change.[3] With high confidence, Boko et al. (2007) projected that in many African countries and regions, agricultural production and food security would likely be severely compromised by climate change and climate variability.[4]

On small islands, sea level rise is expected to exacerbate inundation, erosion and other coastal hazards, and threaten vital infrastructure, human settlements and facilities that support the livelihood of island communities.[5] In the coastal zone of Asia, there are 11 megadeltas with an area greater than 10,000 km2.[6] These megadeltas are homes to millions of people, and contain diverse ecosystems. Climate change and sea level rise could increase the frequency and level of inundation of Asian megadeltas due to storm surges and floods from river drainage.

Ice-cover changes

Permanent ice cover on land is a result of a combination of low peak temperatures and sufficient precipitation. Some of the coldest places on Earth, such as the dry valleys of Antarctica, lack significant ice or snow coverage due to a lack of snow. Sea ice however maybe formed simply by low temperature, although precipitation may influence its stability by changing albedo, providing an insulating covering of snow and effecting heat transfer. Global warming has the capacity to alter both precipitation and temperature, resulting in significant changes to ice cover. Furthermore, the behaviour of ice sheets, ice caps and glaciers is altered by changes in temperature and precipitation, particularly as regards the behaviour of water flowing into and through the ice.

Arctic sea ice

Arctic sea ice minima in 2005, 2007, and the 1979-2000 average.
Main article: Arctic shrinkage

Recent projections of sea ice loss suggest that the Arctic ocean will likely be free of summer sea ice sometime between 2059 and 2078.[7]

Models showing decreasing sea ice also show a corresponding decrease in polar bear habitat.[8] Some scientists see the polar bear as a species which will be affected first and most severely by global warming because it is a top-level predator in the Arctic,[9] which is projected to warm more than the global average.[10] Recent reports show polar bears resorting to cannibalism,[11] and scientists state that these are the only instances that they have observed of polar bears stalking and killing one another for food.[12]

Antarctica

The collapse of Larsen B, showing the diminishing extent of the shelf from 1998 to 2002

The Antarctic peninsula has lost a number of ice shelves recently. These are large areas of floating ice which are fed by glaciers. Many are the size of a small country. The sudden collapse of the Larsen B ice shelf in 2002[13] took 5 weeks or less and may have been due to global warming.[14] Larsen B had previously been stable for up to 12,000 years.[15]

Concern has been expressed about the stability of the West Antarctic ice sheet. A collapse of the West Antarctic ice sheet could occur "within 300 years [as] a worst-case scenario. Rapid sea-level rise (>1 m per century) is more likely to come from the WAIS than from the [Greenland ice sheet]."[16]

Greenland

As the Greenland ice sheet loses mass from calving of icebergs as well as by melting of ice, any such processes tend to accelerate the loss of the ice sheet.[17]

The IPCC suggest that Greenland will become ice free at around 5C over pre-industrial levels,[citation needed] but subsequent research comparing data from the Eemian period suggests that the ice sheet will remain at least in part at these temperatures.[18] The volume of ice in the Greenland sheet is sufficient to cause a global sea level rise of 7 meters. It would take 3,000 years to completely melt the Greenland ice sheet.[19] This figure was derived from the assumed levels of greenhouse gases over the duration of the experiment. In reality, these greenhouse gas levels are of course affected by future emissions and may differ from the assumptions made in the model.

Glaciers

Main article: Retreat of glaciers since 1850

Glacier retreat not only affects the communities and ecosystems around the actual glacier, but the entire downstream region. The most notable example of this is in India, where river systems such as the Indus and Ganges are ultimately fed by glacial meltwater from the Himalayas. Loss of these glaciers will have dramatic effects on the downstream region, increasing the risk of drought as lower flows of meltwater reduce summer river flows unless summer precipitation increases. Altered patterns of flooding can also affect soil fertility.[20]

The Tibetan Plateau contains the world's third-largest store of ice. Qin Dahe, the former head of the China Meteorological Administration, said that the recent fast pace of melting and warmer temperatures will be good for agriculture and tourism in the short term; but issued a strong warning:

"Temperatures are rising four times faster than elsewhere in China, and the Tibetan glaciers are retreating at a higher speed than in any other part of the world.... In the short term, this will cause lakes to expand and bring floods and mudflows. . . . In the long run, the glaciers are vital lifelines for Asian rivers, including the Indus and the Ganges. Once they vanish, water supplies in those regions will be in peril."[21]

Permafrost regions

See also: Climate change in Russia

Regions of permafrost cover much of the Arctic. In many areas, permafrost is melting, leading to the formation of a boggy, undulating landscape filled with thermokarst lakes and distinctive patterns of drunken trees. The process of permafrost melting is complex and poorly understood since existing models do not include feedback effects such as the heat generated by decomposition.[22][citation needed]

Arctic permafrost soils are estimated to store twice as much carbon as is currently present in the atmosphere in the form of CO2. Warming in the Arctic is causing increased emissions of CO2 and Methane (CH4).[23]

Precipitation and vegetation changes

The Eastern Amazon rainforest may be replaced by Caatinga vegetation as a result of global warming.

Much of the effect of global warming is felt through its influence on rain and snow. Regions may become wetter, drier, or may experience changes in the intensity of precipitation - such as moving from a damp climate to one defined by a mixture of floods and droughts. These changes may have a very severe impact on both the natural world and human civilisation, as both naturally occurring and farmed plants experience regional climate change that is beyond their ability to tolerate.

Amazon

One modeling study suggested that the extent of the Amazon rainforest may be reduced by 70% if global warming continues unchecked, due to regional precipitation changes that result from weakening of large-scale tropical circulation.[24]

Sahara

Some studies suggest that the Sahara desert have been more vegetated during the warmer Mid-Holocene period, and that future warming may result in similar patterns.[25][26][clarification needed]

Sahel

Climate models which realistically[clarification needed] model the West African Monsoon predict "a doubling of the number of anomalously dry years [in the Sahel] by the end of the century".[16][clarification needed]

Desert expansion

Expansion of subtropical deserts is expected as a result of global warming, due to expansion of the Hadley Cell.[27]

Coastal regions

Past sea-level changes and relative temperatures. Global warming is expected to dramatically affect sea level.

Global sea level is currently rising due to the thermal expansion of water in the oceans[28] and the addition of water from ice sheets.[29] Because of this, there low-lying coastal areas, many of which are heavily populated, are at risk of flooding.[30]

Areas threatened by current sea level rise include Tuvalu[31] and the Maldives.[32][unreliable source?] Regions that are prone to storm surges, such as London, are also threatened.[33]

With very high confidence, IPCC (2007) projected that by the 2080s, many millions more people would experience floods every year due to sea level rise.[34] The numbers affected were projected to be largest in the densely populated and low-lying megadeltas of Asia and Africa. Small islands were judged to be especially vulnerable.

Ocean effects

North Atlantic region

See also: Shutdown of thermohaline circulation

It has been suggested that a shutdown of the Atlantic thermohaline circulation may result in relative cooling of the North Atlantic region by up to 8C in certain locations.[35] Recent research suggests that this process is not currently underway.[36]

Tropical surface and troposphere temperatures

In the tropics, basic physical considerations, climate models, and multiple independent data sets indicate that the warming trend due to well-mixed greenhouse gases should be faster in the troposphere than at the surface.[37]

See also

References

  1. ^ a b c Intergovernmental Panel on Climate Change (2007d). "3.3.3 Especially affected systems, sectors and regions". Synthesis report. Climate Change 2007: Synthesis Report. A Contribution of Working Groups I, II, and III to the Fourth Assessment Report of the Integovernmental Panel on Climate Change (IPCC). Geneva, Switzerland: IPCC. Retrieved 2011-09-15. {{cite book}}: Unknown parameter |editors= ignored (|editor= suggested) (help)
  2. ^ Anisimov, O.A.; et al. (2007). "15.3.2 Projected atmospheric changes". Chapter 15: Polar Regions (Arctic and Antarctic). Climate change 2007: impacts, adaptation and vulnerability: contribution of Working Group II to the fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC). Cambridge University Press (CUP): Cambridge, UK: Print version: CUP. This version: IPCC website. ISBN 0521880106. Retrieved 2011-09-15. {{cite book}}: Explicit use of et al. in: |author= (help); Unknown parameter |editors= ignored (|editor= suggested) (help)
  3. ^ Schneider, S.H.; et al. (2007). "19.3.3 Regional vulnerabilities". Chapter 19: Assessing Key Vulnerabilities and the Risk from Climate Change. Climate change 2007: impacts, adaptation and vulnerability: contribution of Working Group II to the fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC). Cambridge University Press (CUP): Cambridge, UK: Print version: CUP. This version: IPCC website. ISBN 0521880106. Retrieved 2011-09-15. {{cite book}}: Explicit use of et al. in: |author= (help); Unknown parameter |editors= ignored (|editor= suggested) (help)
  4. ^ Boko, M.; et al. (2007). "Executive summary". Chapter 9: Africa. Climate change 2007: impacts, adaptation and vulnerability: contribution of Working Group II to the fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC). Cambridge University Press (CUP): Cambridge, UK: Print version: CUP. This version: IPCC website. ISBN 0521880106. Retrieved 2011-09-15. {{cite book}}: Explicit use of et al. in: |author= (help); Unknown parameter |editors= ignored (|editor= suggested) (help)
  5. ^ Mimura, N.; et al. (2007). "Executive summary". Chapter 16: Small Islands. Climate change 2007: impacts, adaptation and vulnerability: contribution of Working Group II to the fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC). Cambridge University Press (CUP): Cambridge, UK: Print version: CUP. This version: IPCC website. ISBN 0521880106. Retrieved 2011-09-15. {{cite book}}: Explicit use of et al. in: |author= (help); Unknown parameter |editors= ignored (|editor= suggested) (help)
  6. ^ Cruz, R.V.; et al. (2007). "10.6.1 Megadeltas in Asia". Chapter 10: Asia. Climate change 2007: impacts, adaptation and vulnerability: contribution of Working Group II to the fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC). Cambridge University Press (CUP): Cambridge, UK: Print version: CUP. This version: IPCC website. ISBN 0521880106. Retrieved 2011-09-15. {{cite book}}: Explicit use of et al. in: |author= (help); Unknown parameter |editors= ignored (|editor= suggested) (help)
  7. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1038/ngeo467, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1038/ngeo467 instead.
  8. ^ DeWeaver, Eric (2007). "Uncertainty in Climate Model Projections of Arctic Sea Ice Decline: An Evaluation Relevant to Polar Bears" (PDF). USGS Science Strategy to Support U.S. Fish and Wildlife Service Polar Bear Listing Decision. USGS Administrative Report. p. 40. Retrieved 2009-04-05.
  9. ^ Stirling, I (1993). "Possible impacts of climatic warming on polar bears". Arctic. 46 (3): 240–245. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  10. ^ . ISBN 9780521617789. {{cite book}}: Missing or empty |title= (help)
  11. ^ Amstrup, Steven C.; Stirling, Ian; Smith, Tom S.; Perham, Craig; Thiemann, Gregory W. (2006). "Recent observations of intraspecific predation and cannibalism among polar bears in the southern Beaufort Sea". Polar Biology. 29: 997. doi:10.1007/s00300-006-0142-5.
  12. ^ Jolling, Dan (13 June 2008). "Study: Polar bears may turn to cannibalism". USA Today. Retrieved 2009-04-05.
  13. ^ Hulbe, Christina (2002) "Larsen Ice Shelf 2002, warmest summer on record leads to disintegration" website of Portland State University, online
  14. ^ Antarctic Ice Shelf Collapse Triggered By Warmer Summers Office of News Services, University of Colorado at Boulder, Jan. 16, 2001
  15. ^ Domack E, Duran D, Leventer A, Ishman S, Doane S, Scott McCallum, Amblas D, Ring J, Gilbert R, Prentice M (4 August 2005). "Stability of the Larsen B ice shelf on the Antarctic Peninsula during the Holocene epoch". Nature. 436 (7051): 681–5. doi:10.1038/nature03908. PMID 16079842. {{cite journal}}: Unknown parameter |laydate= ignored (help); Unknown parameter |laysource= ignored (help); Unknown parameter |laysummary= ignored (help)CS1 maint: multiple names: authors list (link)
  16. ^ a b Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1073/pnas.0705414105, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1073/pnas.0705414105 instead.
  17. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1126/science.1072708, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1126/science.1072708 instead.
  18. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1088/1755-1307/6/1/012008, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1088/1755-1307/6/1/012008 instead.
  19. ^ Lowe, Jason (January 2006). "The Role of Sea-Level Rise and the Greenland Ice Sheet in Dangerous Climate Change: Implications for the Stabilisation of Climate" (PDF). UK Met Office. Retrieved 2009-03-29. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help) [dead link‍]
  20. ^ Stephen J. Banta (1985). Wetland soils: characterization, classification, and utilization : proceedings of a workshop held 26 March to 5 April 1984. International Rice Research Institute. ISBN 9711041391.
  21. ^ Global warming benefits to Tibet: Chinese official. Reported 18/Aug/2009.
  22. ^ Pearce, Fred (28 March 2009). "Arctic meltdown is a threat to humanity". New Scientist. No. 2701.
  23. ^ UNEP Year Book2010, An Overview of Our Changing Environment, United Nations Environment Programme 2010 page 36
  24. ^ Cook (June 2007). "Effects of 21st Century Climate Change on the Amazon rainforest" (PDF). Journal of Climate. Retrieved 2009-03-29. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  25. ^ Claussen, Martin (Sep., 1997). "The Greening of the Sahara during the Mid-Holocene: Results of an Interactive Atmosphere-Biome Model". Global Ecology and Biogeography Letters, Vol. 6, No. 5. Blackwell Publishing. pp. 369–377. Retrieved 2009-03-29. {{cite web}}: Check date values in: |date= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  26. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1023/A:1022115604225, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1023/A:1022115604225 instead.
  27. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1029/2006GL028443, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1029/2006GL028443 instead.
  28. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1038/330127a0, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1038/330127a0 instead.
  29. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1111/j.1365-246X.1989.tb06010.x, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1111/j.1365-246X.1989.tb06010.x instead.
  30. ^ "Coastal regions statistics - Statistics explained". European Commission Eurostat. European Commission. Wednesday, 10 December 2010. Retrieved 2011-01-15. {{cite web}}: Check date values in: |date= (help)
  31. ^ [unreliable source?]Adams, Jonathan (May 3, 2007). "Rising sea levels threaten small Pacific island nations". International Herald Tribune. Retrieved 2009-03-29.
  32. ^ Bryant, Nick (Wednesday, 28 July 2004). "Maldives: Paradise soon to be lost". BBC News website. BBC. Retrieved 2009-03-29. {{cite web}}: Check date values in: |date= (help)
  33. ^ Rowson, Jessica. "thames-flood-barrier-upgrade-ruled-out". New Civil Engineer. Retrieved 2009-03-29.
  34. ^ IPCC (2007). "3.3.1 Impacts on systems and sectors. In (section): Synthesis Report. In: Climate Change 2007: Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (Core Writing Team, Pachauri, R.K and Reisinger, A. (eds.))". Book version: IPCC, Geneva, Switzerland. This version: IPCC website. Retrieved 2010-04-10.
  35. ^ Vellinga M, Wood RA (2002). "Global Climatic Impacts of a Collapse of the Atlantic Thermohaline Circulation". Climatic Change. 54: 251–267. doi:10.1023/A:1016168827653.
  36. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1038/448844b, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1038/448844b instead.
  37. ^ Consistency of modelled and observed temperature trends in the tropical troposphere, B. D. Santer, P. W. Thorne, L. Haimberger, K. E. Taylor, T. M. L. Wigley, J. R. Lanzante, S. Solomon, M. Free, P. J. Gleckler, P. D. Jones, T. R. Karl, S. A. Klein, C. Mears, D. Nychka, G. A. Schmidt, S. C. Sherwood, and F. J. Wentz; International Journal of Climatology 28 1703—1722 (2008)
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