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September 4th, 2008

Global sea-level rise may be lower than predicted

Tad Pfeffer and his colleagues Joel Harper (U of Montana) and Shad O'Neel (Scripps UCSD, former INSTAAR) made calculations that show that global sea level rise of much more than 6 feet by the end of this century is a near physical impossibility. In contrast, some scientists have predicted 20 feet or more. Pfeffer's team took a new approach based on simple physical considerations of how fast ice and water can move into the ocean. The team based its work on thermal expansion of ocean water and the glaciological conditions of Greenland, Antarctica and the world's smaller glaciers and ice caps--the three primary contributors to sea rise. They discovered that a total sea level rise of about 6 feet by 2100 could occur under physically possible glaciological conditions but only if all variables are quickly accelerated to extremely high limits.

The team's most likely estimate of roughly 3 to 6 feet by 2100 is still potentially devastating to huge areas of the world in low-lying coastal areas. For example, regions of Bangladesh, China and elsewhere could be devastated, while coastal cities such as New Orleans, Amsterdam or Venice could be swamped. The team's work was published in the September 5th issue of Science.

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