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Melting Now Causing Tides to Rise the Most November 21, 2008
Embankment Photo of Big Ben
Current flood-protection facilities are likely to be ineffective later this century in protecting major population centers from rising sea levels.
Melting water from ice caps in Antarctica and Greenland, and that from mountain glaciers worldwide, has replaced warmer temperatures as the main force behind rising sea levels, according to a new study.

Using sensitive satellite altimeter observations, Anny Cazenave of France’s National Centers for Space Studies found that thermal expansion of the seas virtually stopped after 2003 due to a respite in ocean warming.

Satellite-based gravity measurements of the Earth revealed that the Greenland ice sheet is losing about 150 gigatons of ice each year.

Combined with the loss of ice in West Antarctica, observations show that melting has contributed about 1 millimeter (.04 inches) per year to the rising seas over the past five years.

Ocean levels have been rising since 1993 by almost double the rate they did during the previous 50 years.

The trend could have disastrous impacts on millions of people who live in low-lying areas.

Greenland's ice sheet alone contains enough water to raise the world's ocean levels by 23 feet ( 7 metres) in the unlikely event it should melt entirely.

The U.N. Intergovernmental Panel on Climate Change (IPCC) warned in a report last year that thermal expansion will push sea levels up 7 to 23 inches (18 to 59 centimetres) by 2100.

That would be high enough to wipe out several small island nations and swamp thousands of coastal communities.

Photo: Edward Shaw - iStockphto