Ice melt in Greenland 'could put London under water in 50 years'
The Independent (U.K.), April 8, 2004
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) in a study reported in the journal Nature. 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.
Global Warming Could Melt Greenland Ice Sheet - Study
LONDON - Greenland's huge ice sheet could melt within the next 1,000 years and swamp low-lying areas around the globe if emissions of carbon dioxide (CO2) and global warming are not reduced, scientists said yesterday.
A meltdown of the massive ice sheet, which is more than three km (1.8 miles) thick would raise sea levels by an average seven meters (yards), threatening countries such as Bangladesh, island in the Pacific and parts of Florida.
"Any area that is less than seven meters above sea level would be flooded," said Jonathan Gregory, a climate scientist at the University of Reading in southern England.
Researchers have already calculated that an annual average temperature rise of more than three degrees Celsius would be sufficient to melt the ice sheet in the future.
Gregory and his colleagues have produced new calculations, which are published in the science journal Nature, showing that a temperature rise of that degree is indeed likely to happen.
"We found that the levels of CO2 which we could quite likely reach during this century are sufficient to produce that amount of warming," he said.
Using methods developed for the Intergovernmental Panel on Climate Change, Gregory and his team did modeling studies of temperature change in response to increasing concentrations of greenhouse gases over the next 350 years.
"We estimated what that meant for the temperature of Greenland to see whether it passed the critical level threshold," Gregory added.
Some of the models forecast a temperature rise that was nearly three times more than the threshold.
"How quickly it would happen would depend on how severe the warming was," Gregory said when asked when the ice sheet would disappear. "It is a great deal of ice."
Under the Kyoto Protocol, the European Union must cut its greenhouse gas output by eight percent of 1990 levels between 2008 and 2012. To help reach these targets, the EU has designed an international emissions trading scheme, due to start in 2005.
Plants in each member state will be granted tradeable CO2 certificates which allow them to generate a set amount of the polluting gas.
But it may not be enough.
"Presuming the calculations are right, that it is going to happen, and that we are in the right ball park then you would prevent it (the meltdown) happening by not allowing CO2 to go above the levels we were considering," Gregory said.
The lowest CO2 concentration scenario used in the models was 450 parts per million. Current levels are below that, according to Gregory, but by the middle of this century are likely to exceed it.
"It would not be impossible to remain below that level, if it is the important threshold, but it will mean greater emissions reduction than is currently being considered," he added.