Global warming could melt Greenland ice sheet

LONDON April 11 - 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 on Wednesday.
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 metres (yards), threatening countries such as Bangladesh, island in the Pacific and parts of Florida.
``Any area that is less than seven metres 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 modelling 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.
It did.
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. - Reuters