Scientists at a climate change summit in Copenhagen said earlier UN estimates were too low and that sea levels could rise by a metre or more by 2100.

The projections did not include the potential impact of polar melting and ice breaking off, they added.

The implications for millions of people would be "severe", they warned. Ten per cent of the world's population - about 600 million people - live in low-lying areas.

The UN's Intergovernmental Panel on Climate Change (IPCC), in its 2007 Fourth Assessment Report, had said that the maximum rise in sea level would be in the region of 59cm.

Professor Konrad Steffen from the University of Colorado, speaking at a press conference on Tuesday, highlighted new studies into ice loss in Greenland, showing it has accelerated over the last decade.

Professor Steffen, who has studied the Arctic ice for the past 35 years, told me: "I would predict sea level rise by 2100 in the order of one metre; it could be 1.2m or 0.9m.

"But it is one metre or more seeing the current change, which is up to three times more than the average predicted by the IPCC."

"It is a major change and it actually calls for action."

Dr John Church of the Centre for Australian Weather and Climate Research added: "The most recent research showed that sea level is rising by 3mm a year since 1993, a rate well above the 20th century average."

Ice flow

Professor Eric Rignot, a senior research scientist at Nasa's Jet Propulsion Laboratory, said that results gathered since the IPCC showed that melting and ice loss could not be overlooked.

"As a result of the acceleration of outlet glaciers over large regions, the ice sheets in Greenland and Antarctica are already contributing more and faster to sea level rise than anticipated," he observed.

Professor Stefan Ramstorf of the Potsdam Institute for Climate Impact Research said: "Based on past experience, I expect that sea level rise will accelerate as the planet gets hotter."

 Source : BBC News