Ice melt in Greenland 'could put London under water in 50 years'

A dramatic and irreversible rise in sea levels could result from the melting of the Greenland ice sheet if global warming continues unchecked.

A dramatic and irreversible rise in sea levels could result from the melting of the Greenland ice sheet if global warming continues unchecked.

Scientists say the melting of the massive ice sheet on Greenland - which has been stable for thousands of years - could increase sea levels by as much as 7 metres (23 feet). Such a rise would inundate vast areas of land, including cities at sea level, such as London. Some densely populated regions, such as Bangladesh, may disappear.

For the ice sheet to begin melting, ambient temperatures around Greenland would need to rise more than 3 degrees Celsius, Jonathan Gregory, a climate scientist with the Met Office Hadley Centre and the University of Reading, said. The concentrations of man-made greenhouse gases would probably reach levels that would trigger the melting by about the middle of the century.

"As well as raising sea levels significantly, loss of the Greenland ice sheet would greatly alter the climate of Greenland," Dr Gregory said. "Unlike the ice on the Arctic Ocean, much of which melts and re-forms each year, the Greenland ice sheet might not re-grow even if the global climate were returned to pre-industrial conditions."

A study in the journal Nature by Dr Gregory and his colleagues Philippe Huybrechts and Sarah Raper of the Alfred Wegener Institute in Bremerhaven, Germany, said the melting could become irreversible even if pollution was curtailed.

Under the most extreme scenario of global warming portrayed by the International Panel on Climate Change (IPCC), average temperatures could rise by 8C which would lead to the total disappearance of the Greenland ice sheet within 1,000 years. "The Greenland ice sheet is likely to be eliminated by anthropogenic climate change unless much more substantial emission reductions are made than those envisaged by the IPCC," the scientists say.

"This would mean a global average sea-level rise of 7 metres during the next 1,000 years or more," they add.