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[[File:Icesheet-Map.jpg|thumb|Map showing the West and East Antarctic Ice Sheets]] | [[File:Icesheet-Map.jpg|thumb|Map showing the West and East Antarctic Ice Sheets]] | ||
The '''Western Antarctic Ice Sheet''' (WAIS) is the segment of the continental ice sheet that covers [[Westarctica]] and the portion of [[Antarctica]] on the side of the [[Transantarctic Mountains]] which lies in the Western Hemisphere. The WAIS is classified as a marine-based ice sheet, meaning that its bed lies well below sea level and its edges flow into floating [[ice-shelf|ice shelves]]. The WAIS is bounded by the [[Ross Ice Shelf]], the [[Ronne Ice Shelf]], and outlet | The '''Western Antarctic Ice Sheet''' (WAIS) is the segment of the continental [[ice sheet]] that covers [[Westarctica]] and the portion of [[Antarctica]] on the side of the [[Transantarctic Mountains]] which lies in the Western Hemisphere. The WAIS is classified as a marine-based ice sheet, meaning that its bed lies well below sea level and its edges flow into floating [[ice-shelf|ice shelves]]. The WAIS is bounded by the [[Ross Ice Shelf]], the [[Ronne Ice Shelf]], and outlet [[glacier]]s that drain into the [[Amundsen Sea]]. | ||
It is estimated that the volume of the [[Antarctic ice sheet]] is about 25.4 million km3 (6.1 million cu mi), and the WAIS contains just under 10% of this, or 2.2 million km3 (530,000 cu mi). The weight of the ice has caused the underlying rock to sink by between 0.5 and 1 kilometer (0.31 and 0.62 miles) in a process known as isostatic depression. | It is estimated that the volume of the [[Antarctic ice sheet]] is about 25.4 million km3 (6.1 million cu mi), and the WAIS contains just under 10% of this, or 2.2 million km3 (530,000 cu mi). The weight of the ice has caused the underlying rock to sink by between 0.5 and 1 kilometer (0.31 and 0.62 miles) in a process known as isostatic depression. | ||
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Rapley said, "Parts of the [[Antarctic ice sheet]] that rest on bedrock below sea level have begun to discharge ice fast enough to make a significant contribution to sea level rise. Understanding the reason for this change is urgent in order to be able to predict how much ice may ultimately be discharged and over what timescale. Current computer models do not include the effect of liquid water on ice sheet sliding and flow, and so provide only conservative estimates of future behavior." | Rapley said, "Parts of the [[Antarctic ice sheet]] that rest on bedrock below sea level have begun to discharge ice fast enough to make a significant contribution to sea level rise. Understanding the reason for this change is urgent in order to be able to predict how much ice may ultimately be discharged and over what timescale. Current computer models do not include the effect of liquid water on ice sheet sliding and flow, and so provide only conservative estimates of future behavior." | ||
[[File:Pine-Island-Glacier-Chart.jpg|700px|thumb|center|Ice retreat and thinning since a warm pulse kicked off an irreversible melting in 1945]] | |||
Polar ice experts from the US and UK met at the University of Texas at Austin in March, 2007 for the West Antarctic Links to Sea-Level Estimation (WALSE) Workshop. The experts discussed a new hypothesis that explains the observed increased melting of the West Antarctic Ice Sheet. They proposed that changes in air circulation patterns have led to increased upwelling of warm, deep ocean water along the coast of [[Antarctica]] and that this warm water has increased melting of floating ice shelves at the edge of the ice sheet. An ocean model has shown how changes in winds can help channel the water along deep troughs on the sea floor, toward the ice shelves of outlet glaciers. | Polar ice experts from the US and UK met at the University of Texas at Austin in March, 2007 for the West Antarctic Links to Sea-Level Estimation (WALSE) Workshop. The experts discussed a new hypothesis that explains the observed increased melting of the West Antarctic Ice Sheet. They proposed that changes in air circulation patterns have led to increased upwelling of warm, deep ocean water along the coast of [[Antarctica]] and that this warm water has increased melting of floating ice shelves at the edge of the ice sheet. An ocean model has shown how changes in winds can help channel the water along deep troughs on the sea floor, toward the ice shelves of outlet glaciers. | ||
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==Warming== | ==Warming== | ||
[[File:West Antarctic Warming Graphic.png|thumb|Graphic showing warming on the West Antarctic Ice Sheet]] | [[File:West Antarctic Warming Graphic.png|thumb|Graphic showing warming on the West Antarctic Ice Sheet]] | ||
The West Antarctic Ice Sheet has warmed by more than 0.1 °C (0.18 °F)/decade in the last fifty years, and the warming is the strongest in winter and spring. Although this is partly offset by fall cooling in [[East Antarctica]], this effect was restricted to the 1980s and 1990s. The continent-wide average surface temperature trend of [[Antarctica]] is positive and statistically significant at >0.05 °C (0.090 °F)/decade since 1957. This warming of WAIS is strongest in the [[Antarctic Peninsula]]. In 2012, the temperature records for the ice sheet were reanalyzed with a conclusion that since 1958, the West Antarctic ice sheet had warmed by 2.4 °C (4.3 °F), almost double the previous estimate. Some scientists now fear that the WAIS could now collapse like the [[Larsen B Ice Shelf]] did in 2002. | The West Antarctic Ice Sheet has warmed by more than 0.1 °C (0.18 °F)/decade in the last fifty years, and the warming is the strongest in winter and spring. Although this is partly offset by fall cooling in [[East Antarctica]], this effect was restricted to the 1980s and 1990s. The continent-wide average surface temperature trend of [[Antarctica]] is positive and statistically significant at >0.05 °C (0.090 °F)/decade since 1957. This warming of WAIS is strongest in the [[Antarctic Peninsula]]. In 2012, the temperature records for the ice sheet were reanalyzed with a conclusion that since 1958, the West Antarctic ice sheet had warmed by 2.4 °C (4.3 °F), almost double the previous estimate. Some scientists now fear that the WAIS could now collapse like the [[Larsen-B Ice Shelf]] did in 2002. | ||
[[Category:Science]] | [[Category:Science]] | ||
[[Category:Geography of Westarctica]] | |||