Burning all of the world's available fossil-fuel resources would result in the complete melting of the Antarctic ice sheet, leading to a 50-60-metre (160 to 200 feet) rise in sea level, a study says.
"If we were to burn all attainable fossil fuel resources, this would eliminate the Antarctic ice sheet and cause long-term global sea-level rise unprecedented in human history," warned lead author Ricarda Winkelmann of the Potsdam Institute for Climate Impact Research in Germany.
"This would not happen overnight, but the mind-boggling point is that our actions today are changing the face of planet Earth as we know it, and will continue to do so for tens of thousands of years to come," Winkelmann said.
"If we want to avoid Antarctica to become ice-free, we need to keep coal, gas and oil in the ground," she noted.
The new calculations showed that Antarctica's long-term contribution to sea-level rise could likely be restricted to a few metres that could still be manageable, if global warming did not exceed two degrees.
Crossing this threshold, however, would in the long run destabilise both West and East Antarctica - causing sea-level rise that would reshape coastal regions around the globe for millennia to come.
The long-term risk increases with every additional tenth of a degree of warming, the study said.
"By using more and more fossil energy, we increase the risk of triggering changes that we may not be able to stop or reverse in the future," study co-author Anders Levermann of the Potsdam Institute explained.
"The West Antarctic ice sheet may already have tipped into a state of unstoppable ice loss, whether as a result of human activity or not. But if we want to pass on cities like Tokyo, Hong Kong, Shanghai, Calcutta (Kolkata), Hamburg or New York as our future heritage, we need to avoid a tipping in East Antarctica," he said.
The researchers calculated that burning all available fossil-fuel resources would result in carbon emissions of about 10,000 billion tonnes.
The study took into account the impacts of atmospheric and ocean warming on the Antarctic ice as well as feedback mechanisms that might speed up ice discharge and melting processes.
The study appeared in the journal Science Advances.