By Matthew Green

Scientists believe that global warming has already caused so much melting at the south pole that the giant ice sheet is now on course to disintegrate, which would trigger an eventual global sea level rise of at least three metres over centuries.

The authors of the new study envisaged using 12,000 wind turbines to pump seawater 1,500 metres up to the surface, where it would be frozen into ‘snow’ to try to weigh the sheet down enough to stop it collapsing any further.

“We have already awoken the giant at the southern pole,” said Anders Levermann, a professor at Germany’s Potsdam Institute for Climate Impact Research, referring to the ice sheet.

“We are already at a point of no return if we don’t do anything,” Levermann, who co-authored the study in Science Advances, told Reuters. “We can bring it back to the stable point by a small interference now – or by larger and larger interference later.”

With the droughts, floods, storms and wildfires associated with climate change intensifying globally, some scientists have begun to seriously contemplate interventions that would have been dismissed as wildly impractical even a few years ago.

Echoing many other climate scientists, Levermann said the most urgent priority was to undertake the rapid cuts in carbon emissions needed to meet the temperature goals of the 2015 Paris Agreement, which is aimed at averting runaway climate impacts.

Although Levermann said the full sea level rise projected to follow the collapse of the West Antarctic Ice Sheet might not unfold for hundreds of years, he said he published the paper out of concern for the fate of low-lying populations.

“The sea level rise from Western Antarctica will eventually submerge Hamburg, Shanghai, New York and Hong Kong,” said Levermann, a physicist and oceanographer who is also affiliated with Columbia University in the United States. “You can’t negotiate with physics: that’s the dilemma here.”

Levermann and his authors used computer models to calculate that the West Antarctic ice sheet could be stabilized by depositing a minimum of 7,400 gigatonnes of artificial snow over 10 years around the Pine Island and Thwaites glaciers.

The paper did not give a cost for such an intervention, which Levermann suggested could be borne by governments intent on protecting coastal cities.

(Reporting by Matthew Green, Editing by William Maclean)