Environment Counts | Climate change impact in the Arctic
Author: Wendy Aritenang – Published At: 2012-03-18 04:14 – (897 Reads)
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Net loss of mass from the Greenland Ice sheet has increased from an estimated 50 Gt per year (50 000 000 000 metric tonnes per year) in the period 1995–2000 to ~200 Gt per year in the period 2004–2008. The current loss (~200 Gt per year) represents enough water to supply more than one billion city-dwellers. Nearly all glaciers and ice caps in the Arctic have shrunk over the past 100 years. The rate of ice loss increased over the past decade in most regions, but especially in Arctic Canada and southern Alaska. Total loss of ice from glaciers and smaller ice caps in the Arctic probably exceeded 150 Gt per year in the past decade, similar to the estimated amount being lost from the Greenland Ice Sheet.
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The Artic Monitoring and Assessment Programme /AMAP’s new assessment of the impacts of climate change on Snow, Water, Ice and Permafrost in the Arctic (SWIPA) brings together the latest scientific knowledge about the changing state of each component of the Arctic ‘cryosphere’. It examines how these changes will impact both the Arctic as a whole and people living within the Arctic and elsewhere in the world.‘Cryosphere’ is the scientific term for that part of the Earth’s surface that is seasonally or perennially frozen. It includes snow, frozen ground, ice on rivers and lakes, glaciers, ice caps, ice sheets and sea ice.
The Arctic is warming. Surface air temperatures in the Arctic since 2005 have been higher than for any five-year period since measurements began around 1880. The increase in annual average temperature since 1980 has been twice as high over the Arctic as it has been over the rest of the world. Evidence from lake sediments, tree rings and ice cores indicates that Arctic summer temperatures have been higher in the past few decades than at any time in the past 2000 years. Previously unseen weather patterns and ocean currents have been observed, including higher inflows of warm water entering the Arctic Ocean from the Pacific. These changes are the main drivers of change in the Arctic cryosphere.
Climate-cryosphere interactions may now be accelerating warming. The greatest increase in surface air temperature has happened in autumn, in regions where sea ice has disappeared by the end of summer. This suggests that the sea is absorbing more of the sun’s energy during the summer because of the loss of ice cover. The extra energy is being released as heat in autumn, further warming the Arctic lower atmosphere. Over land, the number of days with snow cover has changed mostly in spring. Early snow melt is accelerated by earlier and
stronger warming of land surfaces that are no longer snow covered.
Source : SWIPA 2011 Executive Summary
