'Ice plugs' keep giant reservoir of East Antarctic ice from sliding into the sea

POTSDAM, Germany, May 5 (UPI) -- There's a giant bowl of ice in East Antarctica that sits below sea level, and could -- if allowed to slip free -- cause sea level to rise more than a dozen feet. Luckily, as researchers recently discovered, it's held back by several "ice plugs."

Ice sheets are constantly in flux, adding new layers of ice on land while losing chunks as it melts into the ocean or calves off in the form of icebergs. Typically, ice sheets maintain some degree of "balance" -- their mass remaining stable as they add as much ice as they lose. But during extended periods of warmer weather, the loss of ice can outpace the formation of new layers.

This has been happening on the edges of West Antarctica, the location of much climate change research. But this worrisome phenomenon has been less obvious in East Antarctica.

Part of the reason, as Matthias Mengel and Anders Levermann of the Potsdam Institute for Climate Impact Research in Germany recently discovered, is that large pieces of ice wedged against East Antarctica's rock ridges are acting as plugs, keeping the giant sheet of ice in Wilkes Basin at bay.

Eventually, these plugs could give way, allowing Wilkes Basin's ice to flow into the ocean.

"This is unstoppable when the plug is removed," explained Levermann. "The speed [of removal] we don't know, but it's definitely a threshold."

Levermann and Mengel ran simulations to better understand what role the plugs will play -- and for how long -- in holding back ice loss to the sea in the future.

Their research determined that eventually, if global warming continues, the plugs won't be up to the task, and sea level rise will be accelerated by the melting of East Antarctica ice. It's a reality, though, that Levermann and Mengel admit is a long way off.

"They are also talking about temperatures much higher than they are now," Ian Joughin, a scientist at the University of Washington's Polar Science Center in Seattle, told National Geographic.

It could take thousands of years for the warm water eating away at West Antarctica, Joughin said, to effect Wilkes Basin.