Published: Fri, February 01, 2019
Research | By Raquel Erickson

New Discovery Signals Rapid Decay in Antarctic Glacier

New Discovery Signals Rapid Decay in Antarctic Glacier

A giant, growing cavern two-thirds the area of Manhattan is contributing to the rapid melting of Antarctica's Thwaites Glacier.

The cavity is large enough to have contained 14 billion tons of ice, most of which has melted within the last three years, say researchers.

Before they made the discovery, Nasa researchers were looking for gaps between ice and bedrock at the bottom of Thwaites where ocean water flows in and melts the glacier from underneath.

The paper by Milillo and his co-authors in the journal Science Advances is titled "Heterogeneous retreat and ice melt of Thwaites Glacier, West Antarctica".

But they were shocked to find the hole and then "surprised" to see its "size and explosive growth rate".

"We have suspected for years that Thwaites was not tightly attached to the bedrock beneath it", Eric Rignot, a researcher at NASA's Jet Propulsion Laboratory and study author, said in a news release. All the data was then processed using a technique called radar interferometry to show how the ground below the surface is moving between images.

"[The size of] a cavity under a glacier plays an important role in melting", Milillo says.

"As more heat and water get under the glacier, it melts faster", he said. Previous numerical models for the melting of the glacier used a fixed shape to represent a cavity under the ice and didn't allow for the cavity to change shape or grow. This summer, the U.S. National Science Foundation and the British Natural Environmental Research Council are launching the International Thwaites Glacier Collaboration, a five-year field project that aims to get to the bottom of the glacier's processes and features.

According to the readings, the hidden void is but one ice casualty among a "complex pattern of retreat and ice melt" that's taking place at Thwaites Glacier, sectors of which are retreating by as much as 800 metres (2,625 ft) every year.

The glacier isn't retreating uniformly.

For Thwaites, "We are discovering different mechanisms of retreat", Millilo said. This data also shed some light on another concern about the glacier's grounding line, the point at which the glacier starts to depart from land and float on the sea.

Researchers hope the new findings will help others preparing for fieldwork in the area better understand the ice-ocean interactions. The disappearance of the ice mass would cause sea levels to rise by about two feet as well as making surrounding glaciers more likely to melt rapidly-which could cause an eight foot rise.

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