Al Gore, the former US Vice-President, has become embroiled in a climate change spin row after claiming that the Arctic could be completely ice-free within five years.
Speaking at the Copenhagen climate change summit, Mr Gore said new computer modelling suggests there is a 75 per cent chance of the entire polar ice cap melting during the summertime by 2014.
However, he faced embarrassment last night after Dr Wieslav Maslowski, the climatologist whose work the prediction was based on, refuted his claims.
Dr Maslowski, of the Naval Postgraduate School in Monterey, California, told The Times: “It’s unclear to me how this figure was arrived at.
“I would never try to estimate likelihood at anything as exact as this.”
The blunder follows the controversy over hacked emails from the University of East Anglia’s Climate Research Unit, which sceptics claim suggest scientists manipulated data to strengthen their argument that global warming is man-made.
Mr Gore, who narrated the Oscar-winning climate change documentary An Inconvenient Truth, told the conference that record melting of Polar and Himalayan ice could deprive more than a billion people of access to clean water.
Alluding to Dr Maslowski’s work, he said: “These figures are fresh, I just got them yesterday.
“Some of the models suggest to Dr Maslowski that there is a 75 per cent chance that the entire polar ice cap during some of summer months could be completely ice free within five to seven years.
“There are more than a billion people on the planet who get more than half of their drinking water – many of them all of their drinking water – from the seasonal melting of snow melt and glacier ice.”
His projection strongly contradicted forecasts made eight months ago by the US government agency that the ice cap may nearly vanish in the summer by 2030.
Dr Maslowki said that his latest results give a six-year projection for the melting of 80 per cent of the ice, but he said he expects some ice to remain beyond 2020.
He added: “I was very explicit that we were talking about near-ice-free conditions and not completely ice-free conditions in the northern ocean.”
Following Dr Maslowski’s comments, Mr Gore’s office later said the 75 per cent figure was one used by Dr Maslowksi as a “ballpark figure” several years ago in a conversation with Mr Gore.
Mr Gore’s speech also provoked criticism from leading members of the climate science community, who described the projection as “aggressive”.
Professor Jim Overland, a leading oceanographer at the US National Oceanic and Atmospheric Administration, told The Times: “This is an exaggeration that opens the science up to criticism from sceptics.
“You really don’t need to exaggerate the changes in the Arctic.”
Mark Serreze, of the US National Snow and Ice Data Center in Boulder, Colorado, said: “It’s possible but not likely. We’re sticking with 2030.”
Average global temperatures have increased by 1.3F (0.74C) in the past century, but the mercury has risen at least twice as quickly in the Arctic.
Scientists say the make up of the frozen north polar sea has shifted significantly in recent years as much of the thick year-round ice has given way to thin seasonal ice.
In the summer of 2007, the Arctic ice cap dwindled to a record low minimum extent of 1.7 million square miles in September. The melting in 2008 and 2009 was not as extensive, but still ranked as the second and third greatest decreases on record.
Ice at the North Pole in 1958 and 1959 – not so thick