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Researchers in Potsdam, Germany have modeled what the future might be like in West Antarctica — and it doesn't look good for many of the world's most populated coastal cities.
The scientists specifically looked at a region of Antarctica called the Amundsen Sea sector, and projected what the consequences would be if the ice there broke apart and drifted out to sea. They found that it could lead to an ensuing ice collapse that could contribute an astounding three meters of sea level rise globally. That's right: an average of 10 feet of sea level rise around the world.
Anders Levermann, a coauthor on the study and a scientist at the Potsdam Institute for Climate Impact Research, compared the amount of ice that needs to melt to cause instability to the skin of an onion.
The researchers wanted to know whether or not if that thin layer of ice became unstable, would the problem remain contained to that area of the continent or would it trigger broader — more ominous — instability throughout West Antarctica.
"We find it's not confined at all," Levermann said. "The entire marine part of the West Antarctic ice sheet [in our model] is destabilized, is discharging into the ocean, which means three meters of sea level rise."
'You lose Miami almost immediately.'
The wild card in the model, Levermann conceded, is the timing of these events. The study, published in the Proceedings of the National Academies of Science, refers to the three-meter sea level rise as occurring "over the coming centuries to millennia."
But while the model does not predict the timing well, what it does model with better confidence is how the region's topography and the dynamics of the ice could possibly prevent a catastrophic ice discharge, Levermann said. He said that the model shows that it would not.
"Whatever there is to stop it, is not strong enough," he said.
Levermann warned that while people can abandon coastal areas in the future, some physical legacies of civilization will not be able to be saved in a scenario in which the oceans rise by three meters.
"Cities like New York, or New Orleans, or Hamburg, or Calcutta, or Tokyo, these are the places where we build our heritage for the future," Levermann said. "There will be certain coastal areas, coastal cities, that we cannot protect against three meters of sea level rise."
In such a scenario, he said, "You lose Miami almost immediately."
Eric Rignot, a professor at the University of California, Irvine, as well as a senior research scientist at NASA's Jet Propulsion Laboratory, was the lead author on an alarming study last year that analyzed the retreat of the glaciers in this region. He said that the Amundsen Sea sector alone — where glaciers like Pine Island and Thwaites meet the water — contains enough ice to raise global sea levels by over one meter.
And two meters of sea level rise, he pointed out, would be enough to displace 200 million people globally.
Rignot said that this latest study is preceded by past research on the region.
"The concept that this sector of Antarctica can lead to the collapse the entire West Antarctic ice sheet is not new," Rignot told VICE News. He said that the region has been thought to be unstable for decades.
Rignot thinks the events the Potsdam scientists modeled may actually happen sooner. "Perhaps one of the drawbacks of the paper is that they seem to have a pretty long timescale to collapse the ice sheet," he said.
Small glaciers in the Amundsen Sea sector, like Smith and Pope Glaciers, are retreating quickly, he said — as fast as one to two kilometers per year.
"I'm still in awe seeing how fast Smith and Pope and even Thwaites are changing with time," Rignot said. "If you look at the past 20 years, the changes in these areas are staggering."
Rignot added that based on modeling studies and observations, he thinks in the next century or two "a lot" of the ice could disappear.
"I'm not aware of any modeling study that shows that once this ice is gone, the rest of West Antarctica will remain," he added. "The rest of West Antarctica will follow suit."
But when that will happen, he said, remains uncertain.
Follow Rob Verger on Twitter: @robverger
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