Melting ‘ice plug’ could unleash massive sea level rise, study says

• May 8, 2014
Neko Harbour, Antarctica

Neko Harbour, Antarctica. Creative Commons: Rita Willaert, 2007

A new study in the journal Nature Climate Change has found that a critical region of East Antarctica is more vulnerable to a climate change-induced thaw than previously believed.

This region, known as the Wilkes Basin, holds the largest volume of marine ice connected by subglacial troughs in all of East Antarctica. The ice in the basin is also held in place by a small undersea rim of ice that is vulnerable to global warming.

If rising ocean temperatures cause this ‘ice plug’ to melt, the world’s sea levels would see a massive rise, according to the study’s authors. The Wilkes Basin has enough ice to raise sea levels by three to four meters (10 to 13 feet).

If all of the ice in Antarctica were to melt, sea levels would rise by 53 meters (174 feet).

“[The] Wilkes Basin is like a bottle on a slant. Once uncorked, it empties out,” Matthias Mengel, lead author of the study, said in a statement.

Since 1870, sea levels have risen 195 millimeters (7.7 inches). In the 20th century, sea levels rose at a rate of 1.7 mm per year. A rise of even three meters would doubtless be devastating to coastal cities and agricultural regions, many of which are already grappling with disruptive storm surges and contamination of fresh water supplies.

Study co-author Anders Levermann told National Geographic that once the ‘ice plug’ has melted, there is no going back. “This is unstoppable when the plug is removed,” said Levermann. “The speed [of removal] we don’t know, but it’s definitely a threshold.”

Although the consequences of this Wilkes Basin emptying itself of ice would be dire, there remains time to prevent catastrophe by halting that greenhouse gas emissions that are warming the planet’s oceans.

The simulations performed by the researchers involved scenarios of 400 to 800 years and ocean temperatures 1 to 2.5°C higher than present levels.

While the threat posed by Wilkes Basin ice is far from immediate, melting ice elsewhere on the continent is already contributing substantially to sea level rise. Earlier this year, an international team of researchers estimated that the irreversible melting of Antarctica’s Pine Island Glacier could add as much as one centimeter to ocean levels by 2035.

Meanwhile, sea ice floating off the continent’s shores—and elsewhere in polar regions—is also falling prey to the human-induced rise in temperatures. If this ice were to melt completely, sea levels would rise an additional 4 centimeters.

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