Pace of polar ice melt 'accelerating rapidly.

THE pace at which the Greenland and Antarctic ice sheets are melting is 'accelerating rapidly' and raising the global sea level, according to findings of a study financed by Nasa and published on Tuesday.

The findings suggest that the ice sheets - more so than ice loss from Earth's mountain glaciers and ice caps - have become 'the dominant contributor to global sea level rise, much sooner than model forecasts have predicted.'

This study, the longest to date examining changes to polar ice sheet mass, combined two decades of monthly satellite measurements with regional atmospheric climate model data to study changes in mass.

'That ice sheets will dominate future sea level rise is not surprising - they hold a lot more ice .mass than mountain glaciers,' said lead author Eric Rignot, jointly of Nasa's Jet Propulsion Laboratory and the University of California, Irvine. 'What is surprising is this increased contribution by the ice sheets is already happening,' he said.

Under the current trends, he said, sea level is likely to be 'significantly higher' than levels projected by the United Nations climate change panel in 2007. Isabella Velicogna, co-author of the study, told AFP that the ice sheets lose mass by melting or by breaking apart in blocks of ice, which float into the ocean.

'It's related to the warming of the planet but that was not the point of the paper. We just observed the changes,' said Velicogna, a professor at UC Irvine. 'It's losing mass - much more than was expected many years ago.'