February 6, 2009


Reuters - North America's coastlines would be hit especially hard by rising sea levels if the huge West Antarctic Ice Sheet collapses and melts in a warming world as some experts fear, scientists said.

The loss of that ice sheet alone would inundate some coastal areas, swamping New York, Washington D.C., south Florida, Los Angeles, San Francisco and Seattle, with sea levels in some places higher by 21 feet or more than today, the researchers wrote in the journal Science.

Factors including changes in the Earth's rotation from the loss of the huge ice sheet would make sea level changes highly variable around the globe, they said. The southern Indian Ocean region also would be heavily affected, they added.. . .

"The peak sea level rise occurs on the coasts of the United States -- the New York area and down the coast, the eastern seaboard of the United States," Mitrovica added. "On the West coast, it's even just a little bit bigger."

Mitrovica said this is not imminent, but rather: "It's a time scale of hundreds of years."

The United Nations Intergovernmental Panel on Climate Change estimates a loss of the ice sheet would raise sea levels around the world on average by about 16.5 feet.

But Mitrovica said the additional ocean volume would not be like adding water to a bath tub and watching the level rise equally, due to other complicated factors.

The researchers said the melting of the ice sheet would cause the Earth's rotation axis to shift about a third of a mile from its current position. This would move water from the southern Atlantic and Pacific oceans northward toward North America and into the southern Indian Ocean.