Friday, 20 July 2007

Sea levels may rise by 9 inches this century

he melting of mountain glaciers and ice caps as a result of global warming over the next century is likely to cause bigger than expected increases in sea levels.

An assessment of the volume of water running into the oceans from melting ice caps suggests that sea levels could rise by two to three times the amount previously expected from this source. The study used satellite monitoring to assess the contribution to sea levels made by all land-based ice, except for the two continental-sized ice sheets of Greenland and Antarctica.
t found that the volume of water melting into the sea each year from glaciers and ice caps was 100 cubic miles (417 cubic km), which is almost equal in size to the amount of water in Lake Erie. However, this volume of meltwater is increasing by a further three cubic miles each year because of an acceleration in the rate at which ice caps and glaciers are melting, said Professor Mark Meier, of the University of Colorado. "One reason for doing this study is the widely held view that the Greenland and Antarctic ice sheets will be the principal cause of sea-level rise," Professor Meier said. "But we show that it is the glaciers and ice caps, not the two large ice sheets, that will be the big players in the sea rise for at least the next few generations."

The Intergovernmental Panel on Climate Change (IPCC) estimated that melting ice caps and glaciers will add about three inches (7.6cm) to sea levels this century. But the latest assessment, published in the journal Science, suggests they are more likely to add between four inches and 9.5 inches to global sea levels.

This does not include the rise in sea levels caused by the thermal expansion of water, which could potentially double this figure. A 12-inch rise in sea level can typically cause a shoreline to retreat by 100ft (30m) or more. About 100 million people now live in areas within three feet of sea level.
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