Antarctic ice sheet
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The Antarctic ice sheet is one of the two polar ice caps of the Earth. It covers about 98% of the Antarctic continent and is the largest single mass of ice on Earth. It covers an area of almost 14 million square km and contains 30 million cubic km of ice. That is, approximately 61 percent of all fresh water on the Earth is held in the Antarctic ice sheet, an amount equivalent to 70 m of water in the world's oceans. In East Antarctica, the ice sheet rests on a major land mass, but in West Antarctica the bed can extend to more than 2,500 m below sea level. The land would be seabed if the ice sheet were not there.[1]
Ice enters the sheet through precipitation, and typically leaves the sheet by calving of coastal icebergs that melt once in the ocean. [1].
A 2002 analysis of NASA satellite data from 1979-1999 showed that areas of Antarctica where ice was increasing outnumbered areas of decreasing ice roughly 2:1.[2]. The general trend shows that a warming climate in the southern hemisphere would transport more moisture to Antarctica, causing the interior ice sheets to grow, while calving events along the coast will increase, causing these areas to shrink[1]. More recent satellite data suggests that the total amount of ice in Antarctica has begun decreasing in the past few years although total Antarctic sea ice anomolies have been steadily increasing since 1978 (NSIDC (2006)). [3]. 2007 showed the largest postive anomoly of sea ice in the southern hemisphere since records have been kept starting in 1979 and 2008 is currently on pace to surpass last years record. [4]
It is a common misconception that the melting of floating ice shelves will not raise sea levels. Because ice shelves are made of fresh water, they will be less dense, i.e, have greater volume than sea water even when melted. The volume of the (melted) water contained in the ice shelf is about 3% greater than the volume of the sea water needed to displace the ice shelf. So as it melts that additional 3% will increase sea level slightly.[5]
[edit] See also
- Geography of Antarctica
- Greenland ice sheet
- Ice sheet
- Ice shelf
- Polar ice
- Ross Ice Shelf
- West Antarctic Ice Sheet
- List of Glaciers in Antarctica
[edit] References
- ^ a b c British Antarctic Survey: [1]
- ^ Ramanujan, Krishna (2002-08-22). Satellites Show Overall Increases in Antarctic Sea Ice Cover. Goddard Space Flight Center. Retrieved on 2007-04-21.
- ^ Velicogna, Isabella; Wahr, John & Scott, Jim (2006-03-02), Antarctic ice sheet losing mass, says University of Colorado study, University of Colorado at Boulder, <http://www.eurekalert.org/pub_releases/2006-03/uoca-ais022806.php>. Retrieved on 21 April 2007
- ^ | url = http://arctic.atmos.uiuc.edu/cryosphere/
- ^ Peter Noerdlinger, PHYSORG.COM "Melting of Floating Ice Will Raise Sea Level"
