Antarctic ice sheet is getting thicker

Parts of the west Antarctic ice sheet are getting thicker rather than thinner according to a study that casts doubt on one of the greatest fears surrounding global warming.

Previous studies have suggested that the western ice sheet is unstable and could melt disastrously in a warmer world, causing sea levels to rise by as much as five metres.

However, an investigation by scientists who studied the shrinkage and expansion of ice using satellite radars has found that rather than losing about 21 billion tons of ice a year, west Antarctica is accumulating nearly 27 billion tons.

Ian Joughin, from Nasa's Jet Propulsion Laboratory, and Slawek Tulaczyk, of the University of California Santa Cruz, believe their study is more accurate and extensive than previous work and could indicate a reversal of a 10,000-year trend in glacier shrinkage which began after the last Ice Age. "The ice sheet has been retreating for the last few thousand years, but we think the end of this retreat has come," said Dr Joughin. "But I hesitate to say that we can stop worrying about it."

This latest study covers a limited area of land and the scientists point out that ice sheets in other regions, such as the Pine Island Glacier and the Thwaites Glacier, are thinning.

Most scientists agree that the west Antarctic ice sheet is potentially unstable and even a small amount of melting caused by global warming could release vast amounts of ice into the sea.

But it has proved difficult to monitor what is happening within the Antarctic ice system and a warmer world might cause more snowfall, resulting in more ice on glaciers. Dr Duncan Whingam, a glaciologist at University College London, said: "It's harder than ever to predict how this area of Antarctica is going to evolve."