ENVIRONMENT: Global warming may mean polar ice-cap getting thicker

Global warming could cause ice in one of the world's coldest regions to thicken rather than melt, scientists said yesterday.

The unexpected finding came from British Antarctic Survey researchers, using a hot water drill to penetrate the vast Filchner-Ronne Ice Shelf near the South Pole. The ice shelf is the most massive on the planet, about the size of Spain and up to 1,600 metres thick.

Warming conditions are thought to have caused the break-up of more northerly Antarctic peninsula ice shelves. But the data obtained by the scientists suggests that moderate climate warming would have the opposite effect on the Filchner-Ronne Ice Shelf.

Temperatures at the base of ice shelves are determined by the water with which they are in contact.

The new findings, published in the science journal Nature, suggest that moderate warming would alter the sea circulation to bring cooler waters in contact with the Filchner-Ronne shelf, causing it to thicken.

Oceanographer Keith Nicholls, one of the research team, said: "It's slightly worrying in a way to see the climate system has these tricks up its sleeve. It goes against common sense and makes you wonder how many other tricks it's got to catch us out. There is little doubt that the large Antarctic ice shelves are significant elements in the world's climate system."