Parts of the vast ice sheet of East Antarctica – which holds enough water to raise global sea levels by 53m – could begin an irreversible slide into the sea this century, causing an unstoppable process of global coastal destruction, scientists have warned.

East Antarctica is widely considered to be more stable than the West Antarctic ice sheet but a new study suggests that a large region of the eastern ice sheet is in danger of becoming irreversibly unstable once a relatively thin section of retaining ice on its coast is lost, the researchers said.

The slab of coastal ice – essentially acting as a plug or a cork – is all that is stopping the giant Wilkes Basin ice sheet from slipping into the sea. Once this process begins it will pour vast amounts of water into the oceans for centuries to come, raising global sea levels by between three and four metres.

"East Antarctica's Wilkes Basin is like a bottle on a slant and once uncorked it empties out," said Matthias Mengel of the Potsdam Institute for Climate Research in Germany, and lead author of the study published in the journal Nature Climate Change.

"The East Antarctic ice sheet has long been considered to be stable even under a warmer climate, in contrast to its West Antarctic counterpart. We have now shown that this may not be true," Mr Mengel confirmed.

"This implies that the future sea-level contribution of the East Antarctic ice sheet may be significantly higher than previously estimated.

"This is important for the millions of people who live on the coasts. Every centimetre of sea level rise on top of what is already expected is going to be even more difficult to adapt to," he said. "By emitting more and more greenhouse gases we might trigger responses now that we may not be able to stop in the future," he added.

East Antarctica holds about 10 times the volume of ice than its smaller West Antarctic cousin. Much of the ice in the east lies at high altitude and is kept well below freezing point, but a large proportion of it – enough to raise sea levels by 19m – lies on bedrock that is below sea level, such as the Wilkes Basin.

In March, the Intergovernmental Panel on Climate Change said sea-level rise was one of the most difficult areas to predict, due to the unknown effects in the Antarctic.

"Until recently, only West Antarctica was considered unstable, but now we know that its 10-times-bigger counterpart in the East might also be at risk," said Prof Anders Levermannof the Potsdam Institute. (©Independent News Service)

Irish Independent