Melting 'Ice Plug' In East Antarctica Would Uncork Up To 13 Feet Of Global Sea-Level Rise

By Ben Wolford on May 6, 2014 3:22 PM EDT

East Antarctica could be a bigger threat to the world's coasts than scientists realized. (Photo: NASA)

East Antarctica could be a bigger threat to the world's coasts than scientists realized. (Photo: NASA)

Geographers divide Antarctica, the world's fifth-largest continent, into two unequal halves: East Antarctica and West Antarctica. Known as "marine ice," the ice in the western portion reaches below sea level until it hits the ocean floor. In the east, the ice mostly sits on a landmass above sea level. Because warm oceans can melt ice better than air can, West Antarctica has been considered more vulnerable to the effects of climate change.

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But scientists in Germany this week have challenged the notion of a stable East Antarctica. They say marine ice trapped in an enormous basin could flow into the oceans and raise sea levels by as much as 13 feet over thousands of years. Human-induced global warming over the next two centuries could melt the only thing keeping the basin where it is — an "ice plug," as the scientists call it. If the plug melts, the ensuing slow devastation would be irreversible.

"East Antarctica's Wilkes Basin is like a bottle on a slant," lead-author Matthias Mengel, of Potsdam University, said in a statement. "Once uncorked, it empties out." They describe this potential phenomenon for the first time in the journal Nature.

So far, there hasn't been much evidence of climate change consequences in East Antarctica. But on the other side of the continent, oceanographers and climate scientists have witnessed alarming trends. In March, scientists armed with four decades of satellite imagery reported that crucial glaciers at the edges of West Antarctica are melting at a rate 77 percent faster now than in 1973. These ice shelves are buttresses that hold back millions of tons of heavy ice. Once they are gone, the heavy ice sheet will slump into the sea and displace sea water around the world. There's enough ice in West Antarctica to cause 10 feet of sea-level rise.

East Antarctica is much larger, but because its ice doesn't interact with the ocean, there had been little cause for concern. "We have probably overestimated the stability of East Antarctica so far," says study co-author Anders Levermann. That's because no one had modeled what would happen if only a small bit of ice — the "ice plug" — were to melt. If the plug itself melts, the world's oceans will rise about 3.5 inches. This could happen over the course of 200 years, the researchers say. But the ice that will flow behind it would raise the sea level between 10 feet and 13 feet over the following 5,000 to 10,000 years.

It seems like a long way off, but the trigger is being pulled right now. Greenhouse gases released today could cause the plug to melt relatively soon. And once it's gone, no amount of carbon reduction will stop the basin from drowning the coasts. "This is the underlying issue here," Mengel says. "By emitting more and more greenhouse gases we might trigger responses now that we may not be able to stop in the future."

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