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Impact of Climate Change on PeriGlacial Environments Arctic(a) vs. Antarctica land: 8 X 106 km2 (30% ice) land: 14 X 106 km2 (97% ice) \ substantial \ no terrestrial food \ land mammals \ herbivorous & \ no land mammals \ no herbivorous or terrestrial food insectivorous birds (high diversity) insectivorous birds (low diversity) Tundra ecosystems “tundra” = treeless barrens Global distribution of tundra Arctic ecosystems in Canada N.Arctic = polar desert S.Arctic = tundra Tundra ecosystems Tundra ecosystems are associated with areas of extreme near-polar climate which operates either directly, or through a series of environmental forcings (primarily thaw-layer dynamics) to limit productivity and biodiversity. Tundra climate stations Barrow Tiksi Churchill Iqaluit Gulf Stream Svalbard Frost-free days Treeline Mean annual snowfall (mm) Treeline Permafrost distribution Alaska Siberia Jan 120 150 150 tree growth pollen/seed viability July mean location Polar Front 30 mean #d >10°C 60 frost-free days 240 Boreal forest patchy discontinuous mean #d <0°C Tundra continuous Permafrost Animal life Climate change Hockey Stick - Earth’s Temperature Variations: Past 1000 Years Source: Arctic Climate Impact Assessment website Associated Climate Changes • Global sea-level has increased 1-2 mm/yr; in 80 years a rise in sea level between 3.5 and 34.6 in. (up to 3ft) is expected • Duration of ice cover of rivers and lakes decreased by 2 weeks in N. Hemisphere • Arctic ice has thinned substantially, decreased in extent by 10-15% • Reduced permafrost in polar, subpolar, mountainous regions • Growing season lengthened by 1-4 days in N. Hemisphere • Retreat of continental glaciers on all continents • Snow cover decreased by 10% (reduced solar reflection) Source: Intergovernmental Panel on Climate Change, 2001 Report 79, the size of the summer polar ice cap has shrunk more than 20 pe Recent (post-1950) climate change in polar regions Arctic: • • • • Reduction in sea ice extent and thickness Northward treeline shifts (e.g. E. coast Hudson Bay) Increased lakes, bogs (e.g. Ellesmere Island) Range expansions (e.g. dragonflies - Inuvik - 2000) Antarctic: • Ice shelf disintegration (e.g. N. Larsen & Wordie Shelf) • Spread of flowering plants (e.g. Antarctic hairgrass has expanded its range 25-fold since 1964) • New lichen species colonizing recently deglaciated areas Polar AmplificationFeedbacks • Ice-Albedo Feedback –relevant to retreating perennial ice cover and also over land • Cloud feedback – positive or negative, depending on the height of clouds • Other feedbacks are mainly positive Total Ice Cover/Monthly Anomalies From 1978 to 1996, the trend in the ice extent was -2.2% per decade. Since 1996, the trend has changed to -10.1% per decade suggesting a large acceleration in the decline. Acceleration in the decline makes it difficult for ice to recover because of ice albedo feedback. -10.1%/dec -10.7%/dec Permafrost in Alaska