According to Prof Peter Wadhams of Cambridge University, the ice that forms over the Arctic sea is shrinking so rapidly that it may vanish altogether in four years' time, destroying the natural habitat of animals like polar bears. The mass of ice between northern Russia, Canada and Greenland waxes and wanes with the seasons, currently reaching a minimum size of about four million square km.

Most models, including the latest estimates by the Inter- governmental Panel on Climate Change (IPCC), track the decline in the area covered by ice in recent years to predict the rate at which it will deteriorate. But citing research compiled by Dr. Wieslaw Maslowski, a researcher from the American Naval Postgraduate School, Prof Wadhams said that such predictions failed to spot how quickly climate change is causing the ice to thin.

While the IPCC suggests the ice will remain in place until the 2030s, Dr. Maslowski's study also takes into account the rate at which it is thinning and calculates that it will vanish much more quickly, 'The Daily Telegraph' reported.

Dr. Maslowski's model, along with his claim that the Arctic sea ice is in a "death spiral", were controversial but Prof Wadhams, a leading authority on the polar regions, said the calculations had him "pretty much persuaded."