Antarctic ice melt "unstoppable," scientists say

Scientist say ice is melting in the western Antarctic at an unstoppable pace, bad news for Thai coastal areas already experiencing significant erosion.

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A boat passes a boundary marker between Bang Khun Thian district, Bangkok, and Samut Sakhon province which once stood on dry land. Rising sea levels from melting Antarctic ice can only make the situation worse.  KOSOL NAKACHOL

West Antarctic ice sheet collapse 'unstoppable': NASA

WASHINGTON, AFP — Ice is melting in the western Antarctic at an unstoppable pace, scientists said Monday, warning that the discovery holds major consequences for global sea level rise in the coming decades.

The speedy melting means that prior calculations of sea level rise worldwide made by the Intergovernmental Panel on Climate Change will have to be adjusted upwards, scientists told reporters.

"A large sector of the West Antarctic ice sheet has gone into a state of irreversible retreat. It has passed the point of no return," said Eric Rignot, professor of Earth system science at the University of California Irvine.

"The retreat of ice is unstoppable," he said, noting that surveys have shown there is no large hill at the back of these glaciers that could hold back the melting ice.

This undated photo courtesy of NASA shows Thwaites Glacier in Western Antarctica. A major ice sheet in western Antarctica is melting, and its collapse is predicted to raise global sea level nearly two feet (61 centimeters), scientists said May 12, 2014. AFP PHOTO/NASA/HANDOUT

"This retreat will have major consequences for sea level rise worldwide," he added, anticipating the melting will take place largely in the next two centuries.

"It will raise sea level by 1.2 meters or four feet," said Rignot, whose paper appears in the peer-reviewed Geophysical Research Letters, a journal of the American Geophysical Union.

A pair of published studies document observational changes in the Antarctic in recent years, and predict the future behavior of the melting ice through computer models.

Rignot, a glaciologist at NASA's Jet Propulsion Laboratory, said his study compiled data from satellites, airplanes, ships and ground surveys in the west Antarctic ice sheet.

Retreat of the Pine Island glacier has slowed in recent years, but scientists said that was likely to due to a very rapid retreat it went through at first.

The nearby Thwaites glacier has been speeding up since 2006.

"From year to year things can change a little bit, so it is really important when looking at this observational evidence to look at the long term trend of these glaciers," Rignot said.

A separate study published in the journal Science on Monday found that Thwaites glacier is melting fast and that its collapse could raise global sea level nearly two feet (61 centimeters).

That study was based largely on computer modeling of the future, in addition to airborne radar measurements of the West Antarctic ice sheet that allowed scientists to map the underlying bedrock.

Study author Ian Joughin, a glaciologist at the University of Washington, said the process is now expected to take between 200 and 1,000 years.

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