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Scientists Discover Seafloor Gateways Melting East Antarctica

Mar 16, 2015 04:12 PM EDT
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Scientists have discovered two seafloor gateways that are hastily melting East Antarctica's largest and most rapidly thinning glacier, threatening to raise global sea levels.

Totten Glacier is East Antarctica's largest outlet of ice to the ocean, and now it seems these newfound gateways are allowing warm ocean water to reach the glacier's base and further speed up ice melt. Although scientists have noticed deep, warm water in this area before, until now they had no idea it was compromising coastal ice.

"We now know there are avenues for the warmest waters in East Antarctica to access the most sensitive areas of Totten Glacier," lead author Jamin Greenbaum, from the University of Texas at Austin's Institute for Geophysics (UTIG), said in a press release.

This discovery is especially concerning because ice flowing through the Totten Glacier alone is enough to raise the global sea level by at least 11 feet - that's the same as if the West Antarctic Ice Sheet were to completely disappear. And if this process keeps up, soon its effects will be irreversible - that is, unless atmospheric and oceanic conditions change so that snowfall outpaces coastal melting.

To better understand the state of Totten Glacier, researchers used aircrafts equipped with special radar and laser instruments that can measure ice several miles thick, the shape and elevation of the ice surface, and even the Earth's gravity and magnetic field strengths to determine seafloor shape.

According to the UTIG team, the deeper of the two gateways identified in the study is a three-mile-wide seafloor valley, which extends from the ocean to beneath Totten Glacier. This surprised scientists, as previous satellite analyses indicated that the ice above this valley was resting on solid ground, and not in fact floating.

In some parts of the ocean surrounding Antarctica, especially West Antarctica, it is known that saltier, and thus heavier warm water can be found below cooler water. And as seen with this newfound seafloor valley, it can connect this deep, warm water to the coast and rapidly melt glaciers. And while this phenomenon is well documented in West Antarctica, this new study now shows that East Antarctica is just as vulnerable - though it likely won't completely melt for a few centuries.

"Now we know the ocean is melting ice in an area of the glacier that we thought was totally cut off before," Greenbaum said. "Knowing this will improve predictions of ice melt and the timing of future glacier retreat."

The results were published in the journal Nature Geoscience.

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