Wednesday, January 14, 2009

Seas to rise at varying rates: expert

ABC News Online, Posted 4 hours 34 minutes ago

Sea levels will rise at widely varying rates around the world because of a quirk of the earth's gravity linked to global warming, a leading glaciologist says.

"Everyone thinks sea level rises the same around the world," David Vaughan, of the British Antarctic Survey, told Reuters at the Rothera Base on the Antarctic Peninsula.

"But it doesn't," he said.

Rises could vary by tens of centimetres from region to region if seas gained by an average of one-metre by 2100 as temperatures rise, he said.

Worst-affected nations would have to budget billions of dollars more than others on coastal defences.

Mr Vaughan said big ice sheets on Antarctica and on Greenland have a gravitational pull that lifts the seas around them - water levels around Antarctica, for instance, are higher than if the frozen continent were an open ocean.

As ice thaws, Antarctica would get smaller and its gravitational tug would diminish.

In some places around the continent, the level of the Southern Ocean might even drop despite a flood of fresh water into the oceans.

The effect means that seas will paradoxically rise least where thawing ice pours into the sea and most further away from the point of melt, he said.

"Ice lost from Antarctica has a bigger impact on European sea level rise than ice lost from the European Alps, tonne for tonne," Mr Vaughan said.

- Reuters

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