Antarctic melting: Coastal cities 'will have 2-3 meter-high sea defenses by end of century'

© Alister Doyle
The unexpectedly rapid melting of a giant glacier in East Antarctica may raise the global sea level at least 2 meters, a new study says, adding that such process may be unstoppable.

The research concentrates on the 150 kilometer-long, 30 kilometer-wide Totten Glacier. The glacier is one of the major outlets for the East Antarctic Ice Sheet, the largest mass of ice on Earth, which covers 98 percent of Antarctica.

"While traditional models haven't suggested this glacier can collapse, more recent models have," said Dr Alan Aitken, of the University of Western Australia, a co-author of the study, as cited by Nature Journal.

"We confirm that collapse has happened in the past, and is likely to happen again if we pass a tipping point, which would occur if we had between 3 and 6 degrees of warming above present."

"Totten Glacier is losing ice now, and the warm ocean water that is causing this loss has the potential to also push the glacier back to an unstable place," said the study’s senior author, professor Martin Siegert, of the Grantham Institute at Imperial College London.

The scientists concluded that the huge glacier is even more vulnerable than they thought. The study by scientists from Imperial College London and institutions in Australia, the US and New Zealand was published in Nature Journal.

They have discovered that the glacier “could cross a critical threshold within the next century, entering an irreversible period of very rapid retreat” in case the problem of climate change isn't resolved.

"Totten Glacier is a slumbering giant," said Andy Shepherd, Director of the NERC Centre for Polar Observation and Modelling at the University of Leeds in England.

According to the research, if the glacier "retreats another 100-150km, its front will be sitting on an unstable bed."

The process would trigger a period of rapid retreat for the glacier and make it "withdraw up to 300 kilometers inland" in the following centuries and release "vast quantities of water, contributing up to 2.9 meters to global sea-level rise," the study says.

"Totten Glacier is only one outlet for the ice of the East Antarctic Ice Sheet, but it could have a huge impact. The East Antarctic Ice Sheet is by far the largest mass of ice on Earth, so any small changes have a big influence globally," Siegert said.

READ MORE: Melting of Antarctic ice sheet and 3-meter sea level rise inevitable - study

The scientist later told media that before the end of the 21 century "the great global cities of our planet near the sea will have two- or three-meter (6.5 - 10 feet) high sea defenses all around them."

One more important point revealed in the study is that the glacier also melted during an earlier period of natural global warming in the past.

"During the Pliocene epoch, temperatures were two degrees Celsius higher than they are right now, and CO2 levels in the atmosphere were 400 parts per million,” Siegert said.

The researchers believe that such a melting process could be about to happen again.

Totten Glacier has been an object of scientific research for a long time. In 2015 the researchers discovered warm water underneath a floating portion of the glacier that is accelerating the melting.