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Part of Antarctica Suddenly Started Melting at a Rate of 14 Trillion Gal. a Year

Sometime in 2009, a long-stable, glacier-filled region in Antarctica suddenly began to melt. Fast.
Antarctica. Image: NASA

Sometime in 2009, a long-stable, glacier-filled region in Antarctica suddenly began to melt. Fast.

A team of scientists with the University of Bristol made the alarming observation by looking at data from the CryoSat-2 satellite: The glaciers around the Southern Antarctic Peninsula, which had showed no signs of change through 2008, had begun losing 55 trillion liters (14.5 trillion gallons) of ice a year. And they evidenced no signs of slowing down.

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"Another, previously stable sector of Antarctica has started losing mass," Jonathan Bamber, a professor of physical geography at Bristol, and one of the authors of the startling new paper published in Science, told me. "In addition, this sector looks like it may continue to lose mass for years to decades due to the bedrock geometry."

That sector is a big one: the thawing glaciers stretch across 466 miles (750 km) of coastline, making the region the second-largest contributor to ice melt on the vast continent. Which means it will be a significant contributor to sea level rise worldwide, too.

"We estimate that the potential contribution from this sector is about 20 cm," Bamber said. That's nearly eight inches of sea level rise that's locked-in, he says, just from this lone region in Antarctica. That adds to the total projected sea level rise from the continent, which climbed last year, after the collapse of a major ice sheet all but guaranteed 10 feet of sea level rise. (Perhaps not for centuries, but still.)

"To date, the glaciers added roughly 300 cubic km of water to the ocean," the study's lead author Bert Wouters said in a statement. "That's the equivalent of the volume of nearly 350,000 Empire State Buildings combined." The surface of some of the glaciers the team analyzed was decreasing as much as 4 meters (13 feet) a year. And that's just over the five years since the melt began.

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The ice loss in the region is so large, the scientists say, that it is causing small changes in the Earth's gravity field.

The ice loss in the region is so large, the scientists say, that it is causing small changes in the Earth's gravity field.

So what gives? Why did such a huge chunk of the south pole suddenly start melting into the ocean? "We think it is the shoaling of relatively warm ocean water beneath the ice shelves that buttress the inland ice," Bamber said. The warming climate and depleted ozone have fueled the westerly winds that gust around Antarctica, making them more powerful. In turn, the scientists believe they're pushing warm waters from the Southern Ocean towards the pole, where they thaw the ice shelves and glaciers from beneath.

We already knew that warming ocean waters were dramatically speeding the thinning of the ice shelves that surround Antarctica—another study published in Science earlier this year came to that conclusion. Now we know the damage that thinning can do.

The new findings highlight that, as always with climate change, we should expect the unexpected. In 2008, a massive store of ice was locked away in freezing isolation in south Antarctica. One year later, it's spewing water into the ocean like a jacked fire hydrant. And not even the scientists saw it coming.

"We were surprised how such a large area, ~705 km long, could respond simultaneously in the same way and continue like that since 2009," Bamber said. "We didn't expect to see such a sudden and uniform response over such a large area."

When I sent Bamber a final follow up email asking whether the suddenness of the melt alarmed him about the possibility of other areas following suit, the response came back in a matter of seconds: "Yes it does."