Sea level rise 'to exceed projections'

The global sea level looks set to rise far higher than forecast because of changes in the polar ice-sheets, a team of researchers has suggested. 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. Ten per cent of the world's population - about 600 million people - live in low-lying areas.

The missing factor is the melting of the world's largest temperate glaciers in Alaska and Canada, say Mark Meier and Mark Dyurgerov at the University of Colorado at Boulder. New data from the University of Alaska show this has been underplayed in earlier calculations, they say. Meier and Dyurgerov's new range is much higher, at between 20 and 46 cm, and they say it could be even greater. Combined with the IPCC's estimate for sea level rise caused by other processes, such as ocean warming, of 11 to 43 cm, the total 21st century rise could be as much as 89 cm.

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.

At Lowestoft, on the UK's east coast, the Environment Agency official in charge of coastal protection, David Kemp, said that even small rises in sea level could be overwhelming. "Put bluntly, if it's 10cm below the height of the defence, then there's no problem. But if it's 10cm above the defence, then we could be looking at devastation."

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."

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."