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Changes in the Cryosphere and Global Climate Change

Changes in the Cryosphere and Global Climate Change. Global Warming: The Basic Science. Carbon Dioxide has risen from ~280ppm in 1850 to 379ppm in 2005. Warming is now unequivocal Increase in global average air and ocean temperatures, rising average sea level, melting ice

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Changes in the Cryosphere and Global Climate Change

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  1. Changes in the Cryosphere andGlobal Climate Change

  2. Global Warming: The Basic Science • Carbon Dioxide has risen from ~280ppm in 1850 to 379ppm in 2005. • Warming is now unequivocal • Increase in global average air and ocean temperatures, rising average sea level, melting ice • Primary forcings are anthropogenic greenhouse gases • Fossil fuel burning • Deforestation • Similar increases in methane and nitrous oxide

  3. Why the Cryosphere? • “Canary in the coal mine” • Ice is one of the most sensitive parts of the climate system • Most visible symptom of climate change • Arctic contains 1/3 of the world’s stored carbon • Global decline in snow and ice that is accelerating. Perito Moreno glacier Glacier National Park, Argentina.

  4. Components

  5. Snow Cover • Snow cover has decreased in most regions • Decreases due to temperature • Some specific increases due to precipitation • Could cause long-term freshwater shortages

  6. Sea Ice • Extends and retreats every year • Arctic sea ice extent: -2.7% per decade • Minimum extent (in summer): -7.4% per decade

  7. Recent Dramatic Events • 9/3-9/9: Area of sea ice the size of Florida (69,000 mi2) melts • Northwest Passage open for first time in human history

  8. Glaciers and Ice Caps • Studied in terms of mass balance • 10% of world’s surface covered by glaciers, mostly Greenland and Antarctica • Some date back as far as the last ice age • Rapid and visible melting • Approx. 0.5 SLE 1961-2004; 0.77 SLE 1991-2004; trending higher

  9. Visible Effects

  10. Ice Sheets and Ice Shelves • Defined: Glacier Ice greater than 50,000 km2. The big kahuna of glaciers! • Greenland Ice Sheet: 7.2m SLE! • Antarctic Ice Sheet: 61m SLE! • Ice shelves extend out from connected ice sheets • Melting ice shelves can foreshadow melting ice sheets • Ice sheets very likely already contributing to sea level rise

  11. Greenland and The Antarctic Ward Hunt Ice Shelf • 2003-2005: Greenland ice sheet loses 41 mi3 at margins and gains only 14 mi3 at interior. • Ward Hunt: • Approximately 3,000 years in age • In 2002 it began to break up An ice island about 1.5 kilometers long, 250 meters wide, and 30 meters thick moves into the Arctic ocean after the fracturing of the Ward Hunt Ice Shelf in August 2002. (Image courtesy of Warwick Vincent, Université Laval)

  12. How surface melting accelerates glacier melting

  13. Frozen Ground • The largest part of the cryosphere in terms of surface area • Permafrost can be ancient; some ground only freezes seasonally • Human development on top of permafrost • Cities/towns • Oil pipelines • Roads

  14. Frozen Ground • Tundra/Permafrost • Contains more carbon locked away in frozen soil than the entire atmosphere holds today • Can release its carbon as methane, a more potent greenhouse gas

  15. Impacts on Biodiversity • Many polar species are particularly vulnerable to climate change because they are specifically adapted to that environment. • Food supply • Invasive new species filling niches • Fresh water supply • Melting ice also opens up new areas to explore for human development/extraction/hunting, further threatening polar life.

  16. Case Study: Caribou

  17. Impacts Increases in temperature encourage mosquito harassment Paradoxically, warming is predicted to cause increases in Arctic precipitation, causing increase in snow pack, making feeding difficult.

  18. Who else loses?

  19. Who Benefits from Inaction? • In general, natural resource extraction and refining; new areas open to exploitation • Construction companies; anyone who can make a profit following coastal disasters • Oppressive governments

  20. Prediction Scenarios • Some warming has already occurred; more will likely already occur regardless of anything else • The amount of future warming will depend on a number of different forcings, one of which is human-made emissions • With regard to predictions of future emissions and warming, it is useful to speak in terms of scenarios • See “Summary for Policymakers” at WWW.IPCC.CH – last page

  21. Large-scale Implications of Sea Level Rise • Human population distribution • Large numbers near coasts or major rivers • Coastal ecosystem disruption • Global dilemma • International cooperation required at a time of serious divisions • Mitigating climate change offers a means of encouraging cooperation on other issues

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