Effects of climate change on ecosystems

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This article is about climate change and ecosystems.

Impacts

See also: Extinction risk from global warming, Effect of climate change on plant biodiversity, and Effects of climate change on marine mammals

Unchecked global warming could affect most terrestrial ecoregions. Increasing global temperature means that ecosystems will change; some species are being forced out of their habitats (possibly to extinction) because of changing conditions, while others are flourishing. Secondary effects of global warming, such as lessened snow cover, rising sea levels, and weather changes, may influence not only human activities but also the ecosystem.

For the IPCC Fourth Assessment Report, experts assessed the literature on the impacts of climate change on ecosystems. Rosenzweig et al. (2007) concluded that over the last three decades, human-induced warming had likely had a discernable influence on many physical and biological systems (p. 81).[1] Schneider et al. (2007) concluded, with very high confidence, that regional temperature trends had already affected species and ecosystems around the world (p. 792).[2] With high confidence, they concluded that climate change would result in the extinction of many species and a reduction in the diversity of ecosystems (p. 792).

  • Terrestrial ecosystems and biodiversity: With a warming of 3°C, relative to 1990 levels, it is likely that global terrestrial vegetation would become a net source of carbon (Schneider et al., 2007:792). With high confidence, Schneider et al. (2007:788) concluded that a global mean temperature increase of around 4°C (above the 1990-2000 level) by 2100 would lead to major extinctions around the globe.
  • Marine ecosystems and biodiversity: With very high confidence, Schneider et al. (2007:792) concluded that a warming of 2°C above 1990 levels would result in mass mortality of coral reefs globally.
  • Freshwater ecosystems: Above about a 4°C increase in global mean temperature by 2100 (relative to 1990-2000), Schneider et al. (2007:789) concluded, with high confidence, that many freshwater species would become extinct.

Studying the association between Earth climate and extinctions over the past 520 million years, scientists from the University of York write, "The global temperatures predicted for the coming centuries may trigger a new ‘mass extinction event’, where over 50 per cent of animal and plant species would be wiped out."[3]

Many of the species at risk are Arctic and Antarctic fauna such as polar bears[4] and Emperor Penguins.[5] In the Arctic, the waters of Hudson Bay are ice-free for three weeks longer than they were thirty years ago, affecting polar bears, which prefer to hunt on sea ice.[6] Species that rely on cold weather conditions such as gyrfalcons, and Snowy Owls that prey on lemmings that use the cold winter to their advantage may be hit hard.[7][8] Marine invertebrates enjoy peak growth at the temperatures they have adapted to, regardless of how cold these may be, and cold-blooded animals found at greater latitudes and altitudes generally grow faster to compensate for the short growing season.[9] Warmer-than-ideal conditions result in higher metabolism and consequent reductions in body size despite increased foraging, which in turn elevates the risk of predation. Indeed, even a slight increase in temperature during development impairs growth efficiency and survival rate in rainbow trout.[10]

Rising temperatures are beginning to have a noticeable impact on birds,[11] and butterflies have shifted their ranges northward by 200 km in Europe and North America. Plants lag behind, and larger animals' migration is slowed down by cities and roads. In Britain, spring butterflies are appearing an average of 6 days earlier than two decades ago.[12]

A 2002 article in Nature[13] surveyed the scientific literature to find recent changes in range or seasonal behaviour by plant and animal species. Of species showing recent change, 4 out of 5 shifted their ranges towards the poles or higher altitudes, creating "refugee species". Frogs were breeding, flowers blossoming and birds migrating an average 2.3 days earlier each decade; butterflies, birds and plants moving towards the poles by 6.1 km per decade. A 2005 study concludes human activity is the cause of the temperature rise and resultant changing species behaviour, and links these effects with the predictions of climate models to provide validation for them.[14] Scientists have observed that Antarctic hair grass is colonizing areas of Antarctica where previously their survival range was limited.[15]

Mechanistic studies have documented extinctions due to recent climate change: McLaughlin et al. documented two populations of Bay checkerspot butterfly being threatened by precipitation change.[16] Parmesan states, "Few studies have been conducted at a scale that encompasses an entire species"[17] and McLaughlin et al. agreed "few mechanistic studies have linked extinctions to recent climate change."[16] Daniel Botkin and other authors in one study believe that projected rates of extinction are overestimated.[18] For "recent" extinctions, see Holocene extinction.

Many species of freshwater and saltwater plants and animals are dependent on glacier-fed waters to ensure a cold water habitat that they have adapted to. Some species of freshwater fish need cold water to survive and to reproduce, and this is especially true with Salmon and Cutthroat trout. Reduced glacier runoff can lead to insufficient stream flow to allow these species to thrive. Ocean krill, a cornerstone species, prefer cold water and are the primary food source for aquatic mammals such as the Blue Whale.[19] Alterations to the ocean currents, due to increased freshwater inputs from glacier melt, and the potential alterations to thermohaline circulation of the worlds oceans, may affect existing fisheries upon which humans depend as well.

The white lemuroid possum, only found in the Daintree mountain forests of northern Queensland, may be the first mammal species to be driven extinct by global warming in Australia. In 2008, the White Possum has not been seen in over three years. The possums cannot survive extended temperatures over 30 °C (86 °F), which occurred in 2005.[20]

Forests

Pine forests in British Columbia have been devastated by a pine beetle infestation, which has expanded unhindered since 1998 at least in part due to the lack of severe winters since that time; a few days of extreme cold kill most mountain pine beetles and have kept outbreaks in the past naturally contained. The infestation, which (by November 2008) has killed about half of the province's lodgepole pines (33 million acres or 135,000 km²)[21][22] is an order of magnitude larger than any previously recorded outbreak.[23] One reason for unprecedented host tree mortality may be due to that the mountain pine beetles have higher reproductive success in lodgepole pine trees growing in areas where the trees have not experienced frequent beetle epidemics, which includes much of the current outbreak area.[24] In 2007 the outbreak spread, via unusually strong winds, over the continental divide to Alberta. An epidemic also started, be it at a lower rate, in 1999 in Colorado, Wyoming, and Montana. The United States forest service predicts that between 2011 and 2013 virtually all 5 million acres (20,000 km2) of Colorado’s lodgepole pine trees over five inches (127 mm) in diameter will be lost.[22]

As the northern forests are a carbon sink, while dead forests are a major carbon source, the loss of such large areas of forest has a positive feedback on global warming. In the worst years, the carbon emission due to beetle infestation of forests in British Columbia alone approaches that of an average year of forest fires in all of Canada or five years worth of emissions from that country's transportation sources.[23][25]

Besides the immediate ecological and economic impact, the huge dead forests provide a fire risk. Even many healthy forests appear to face an increased risk of forest fires because of warming climates. The 10-year average of boreal forest burned in North America, after several decades of around 10,000 km² (2.5 million acres), has increased steadily since 1970 to more than 28,000 km² (7 million acres) annually.[26] Though this change may be due in part to changes in forest management practices, in the western U.S., since 1986, longer, warmer summers have resulted in a fourfold increase of major wildfires and a sixfold increase in the area of forest burned, compared to the period from 1970 to 1986. A similar increase in wildfire activity has been reported in Canada from 1920 to 1999.[27]

Forest fires in Indonesia have dramatically increased since 1997 as well. These fires are often actively started to clear forest for agriculture. They can set fire to the large peat bogs in the region and the CO₂released by these peat bog fires has been estimated, in an average year, to be 15% of the quantity of CO₂produced by fossil fuel combustion.[28]

Mountains

Mountains cover approximately 25 percent of earth's surface and provide a home to more than one-tenth of global human population. Changes in global climate pose a number of potential risks to mountain habitats.[29] Researchers expect that over time, climate change will affect mountain and lowland ecosystems, the frequency and intensity of forest fires, the diversity of wildlife, and the distribution of water.

Studies suggest that a warmer climate in the United States would cause lower-elevation habitats to expand into the higher alpine zone.[30] Such a shift would encroach on the rare alpine meadows and other high-altitude habitats. High-elevation plants and animals have limited space available for new habitat as they move higher on the mountains in order to adapt to long-term changes in regional climate.

Changes in climate will also affect the depth of the mountains snowpacks and glaciers. Any changes in their seasonal melting can have powerful impacts on areas that rely on freshwater runoff from mountains. Rising temperature may cause snow to melt earlier and faster in the spring and shift the timing and distribution of runoff. These changes could affect the availability of freshwater for natural systems and human uses.[31]

Ecological productivity

  • According to a paper by Smith and Hitz (2003:66), it is reasonable to assume that the relationship between increased global mean temperature and ecosystem productivity is parabolic. Higher carbon dioxide concentrations will favourably affect plant growth and demand for water. Higher temperatures could initially be favourable for plant growth. Eventually, increased growth would peak then decline.[32]
  • According to IPCC (2007:11), a global average temperature increase exceeding 1.5–2.5°C (relative to the period 1980–99), would likely have a predominantly negative impact on ecosystem goods and services, e.g., water and food supply.[33]
  • Research done by the Swiss Canopy Crane Project suggests that slow-growing trees only are stimulated in growth for a short period under higher CO2 levels, while faster growing plants like liana benefit in the long term. In general, but especially in rainforests, this means that liana become the prevalent species; and because they decompose much faster than trees their carbon content is more quickly returned to the atmosphere. Slow growing trees incorporate atmospheric carbon for decades.

Species migration

In 2010, a gray whale was found in the Mediterranean Sea, even though the species had not been seen in the North Atlantic Ocean since the 18th century. The whale is thought to have migrated from the Pacific Ocean via the Arctic. Climate Change & European Marine Ecosystem Research (CLAMER) has also reported that the Neodenticula seminae alga has been found in the North Atlantic, where it had gone extinct nearly 800,000 years ago. The alga has drifted from the Pacific Ocean through the Arctic, following the reduction in polar ice.[34]

In the Siberian subarctic, species migration is contributing to another warming albedo-feedback, as needle-shedding larch trees are being replaced with dark-foliage evergreen conifers which can absorb some of the solar radiation that previously reflected off the snowpack beneath the forest canopy.[35][36]

References

  1. ^ Rosenzweig, C.; et al. (2007). "Assessment of observed changes and responses in natural and managed systems. In: Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [M.L. Parry et al. (eds.)]". Cambridge University Press, Cambridge, U.K., and New York, N.Y., U.S.A. pp. 79–131. Retrieved 2009-05-20. {{cite web}}: Explicit use of et al. in: |author= (help)
  2. ^ Schneider, S.H.; et al. (2007). "Assessing key vulnerabilities and the risk from climate change. In: Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [M.L. Parry et al. (eds.)]". Cambridge University Press, Cambridge, U.K., and New York, N.Y., U.S.A. pp. 779–810. Retrieved 2009-05-20. {{cite web}}: Explicit use of et al. in: |author= (help)
  3. ^ Mayhew, Peter J (October 23, 2007). "A long-term association between global temperature and biodiversity, origination and extinction in the fossil record". Proceedings of the Royal Society B. 275 (1630). Royal Society Publishing: 47–53. doi:10.1098/rspb.2007.1302. PMC 2562410. PMID 17956842. Retrieved 2007-10-30. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  4. ^ Amstrup, Steven C. (2006-04-27). "Recent observations of intraspecific predation and cannibalism among polar bears in the southern Beaufort Sea". Polar Biology. 29 (11): 997–1002. doi:10.1007/s00300-006-0142-5. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  5. ^ Le Bohec, Céline (2008-02-11). "King penguin population threatened by Southern Ocean warming" (abstract). Proc. Natl. Acad. Sci. U.S.A. 105 (7): 2493–7. Bibcode:2008PNAS..105.2493L. doi:10.1073/pnas.0712031105. PMC 2268164. PMID 18268328. Retrieved 2008-02-13. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  6. ^ On Thinning Ice Michael Byers London Review of Books January 2005
  7. ^ Pertti Koskimies (compiler) (1999). "International Species Action Plan for the Gyrfalcon Falco rusticolis" (PDF). BirdLife International. Retrieved 2007-12-28.
  8. ^ "Snowy Owl" (PDF). University of Alaska. 2006. Retrieved 2007-12-28.
  9. ^ Arendt, J.D. (1997). "Adaptive intrinsic growth rates: an integration across taxa". The Quarterly Review of Biology. 72 (2): 149–177. doi:10.1086/419764. ISSN 0033-5770. JSTOR 3036336.
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  11. ^ Time Hirsch (2005-10-05). "Animals 'hit by global warming'". BBC News. Retrieved 2007-12-29.
  12. ^ Walther, Gian-Reto (March 28, 2002). "Ecological responses to recent climate change" (PDF). Nature. 416 (6879): 389–95. doi:10.1038/416389a. PMID 11919621. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  13. ^ Root, Terry L. (2003-01-02). "Fingerprints of global warming on animals and plants". Nature. 421 (6918): 57–9. doi:10.1038/nature01333. PMID 12511952. Retrieved 2008-02-13. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help) [dead link]
  14. ^ www.stanford.edu
  15. ^ Grass flourishes in warmer Antarctic originally from The Times, December 2004
  16. ^ a b McLaughlin, John F. (2002-04-30). "Climate change hastens population extinctions" (PDF). Proc. Natl. Acad. Sci. U.S.A. 99 (9): 6070–4. Bibcode:2002PNAS...99.6070M. doi:10.1073/pnas.052131199. PMC 122903. PMID 11972020. Archived from the original (PDF) on 2007-06-04. Retrieved 2007-03-29. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  17. ^ Permesan, Camille (2006-08-24). "Ecological and Evolutionary Responses to Recent Climate Change" (PDF). Annual Review of Ecology, Evolution, and Systematics. 37: 637–69. doi:10.1146/annurev.ecolsys.37.091305.110100. Retrieved 2007-03-30.
  18. ^ Botkin, Daniel B. (2007). "Forecasting the Effects of Global Warming on Biodiversity" (PDF). BioScience. 57 (3): 227–236. doi:10.1641/B570306. Retrieved 2007-11-30. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
  19. ^ Lovell, Jeremy (2002-09-09). "Warming Could End Antarctic Species". CBS News. Retrieved 2008-01-02.
  20. ^ Malkin, Bonnie (2008-12-03). "Australia's white possum could be first victim of climate change - Telegraph". The Daily Telegraph. Telegraph Media Group. ISSN 0307-1235. OCLC 49632006. Retrieved 2011-07-30.
  21. ^ Natural Resources Canada
  22. ^ a b Jim Robbins, Beetles Kill Millions of Acres of Trees in West, New York Times, 17 November 2008
  23. ^ a b Kurz WA, Dymond CC, Stinson G; et al. (2008). "Mountain pine beetle and forest carbon feedback to climate change". Nature. 452 (7190): 987–90. Bibcode:2008Natur.452..987K. doi:10.1038/nature06777. PMID 18432244. {{cite journal}}: Explicit use of et al. in: |author= (help); Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  24. ^ Cudmore TJ, Björklund N, Carrollbbb, AL. Lindgren BS. (2010). "Climate change and range expansion of an aggressive bark beetle: evidence of higher reproductive success in naïve host tree populations". Journal of Applied Ecology. 47 (5): 1036–43. doi:10.1111/j.1365-2664.2010.01848.x. {{cite journal}}: Unknown parameter |unused_data= ignored (help)CS1 maint: multiple names: authors list (link)
  25. ^ Pine Forests Destroyed by Beetle Takeover, NPR'sTalk of the Nation, April 25, 2008
  26. ^ US National Assessment of the Potential Consequences of Climate Variability and Change Regional Paper: Alaska
  27. ^ Running SW (2006). "Climate change. Is Global Warming causing More, Larger Wildfires?". Science. 313 (5789): 927–8. doi:10.1126/science.1130370. PMID 16825534. {{cite journal}}: Unknown parameter |month= ignored (help)
  28. ^ BBC News: Asian peat fires add to warming
  29. ^ Nogués-Bravoa D., Araújoc M.B., Erread M.P., Martínez-Ricad J.P. (2007). "Exposure of global mountain systems to climate warming during the 21st Century". Global Environmental. 17 (3–4): 420–8. doi:10.1016/j.gloenvcha.2006.11.007. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  30. ^ The Potential Effects Of Global Climate Change On The United States Report to Congress Editors: Joel B. Smith and Dennis Tirpak US-EPA December 1989
  31. ^ "Freshwater Issues at 'Heart of Humankind'S Hopes for Peace and Development'" (Press release). United Nations. 2002-12-12. Retrieved 2008-02-13.
  32. ^ Smith, J. and Hitz, S. (2003). "OECD Workshop on the Benefits of Climate Policy: Improving Information for Policy Makers. Background Paper: Estimating Global Impacts from Climate Change" (PDF). Organisation for Economic Co-operation and Development. Retrieved 2009-06-19.{{cite web}}: CS1 maint: multiple names: authors list (link)
  33. ^ IPCC (2007). "Summary for Policymakers. In: Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [M.L. Parry et al. (eds.)]". Cambridge University Press, Cambridge, U.K., and New York, N.Y., U.S.A. pp. 7–22. Retrieved 2009-05-20.
  34. ^ Tuesday, 26 July 2011 (27 June 2011). "Plankton species reappears (after being extinct for 800,000 years)". Mother Nature Network. Retrieved 2011-07-27.{{cite web}}: CS1 maint: numeric names: authors list (link)
  35. ^ Shuman, Jacquelyn Kremper (2011). "Sensitivity of Siberian Larch forests to climate change". Global Change Biology. 17 (7): 2370–2384. doi:10.1111/j.1365-2486.2011.02417.x. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  36. ^ "Russian Boreal Forests Undergoing Vegetation Change, Study Shows".

Further reading

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