Published: Fri, February 01, 2019
Sci-tech | By Patricia Wade

Nasa reveals 'disturbing' discovery of huge void in Thwaites Glacier

Nasa reveals 'disturbing' discovery of huge void in Thwaites Glacier

The Thwaites Glacier, the largest outflow channel of the vulnerable West Antarctic Ice Sheet, now has a very big subterranean hole.

Scientists have found a "cavity" melted in the ice that occupies roughly two-thirds the surface area of Manhattan, prompting the space agency say its existence "signals" the ice sheet's "rapid decay". It holds enough ice to raise ocean levels by around two feet.

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.

Thwaites glacier in western Antarctica.

Yet the huge size and fast-moving growth rate of the hole in Thwaites was called both "disturbing" and "surprising" by researchers.

"We have suspected for years that Thwaites was not tightly attached to the bedrock beneath it", study co-researcher Eric Rignot, a professor of Earth system science at the University of California, Irvine, and a principal scientist for the Radar Science and Engineering Section at NASA's Jet Propulsion Laboratory in Pasadena, California, said in a statement.

'Thanks to a new generation of satellites, we can finally see the detail'.

"[The size of] a cavity under a glacier plays an important role in melting", said Pietro Milillo of NASA's Jet Propulsion Laboratory in a news release by the organization.

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By observing the undersides of Antarctic glaciers, researchers hope to calculate how fast global sea levels will rise in response to climate change.

That's important to know, since Thwaites now accounts for about 4 percent of global sea level rise.

The cavity was revealed by ice-penetrating radar in the NASA study into connections between the polar regions and global climate.

Thwaites glacier is one of the most hard places on Earth to reach.

For Thwaites, "We are discovering different mechanisms of retreat", Millilo said. The Thwaites Glacier melting could also lead to nearby glaciers melting, which could lift sea levels around the world an additional eight feet.

Much of that ice disappeared at an "explosive rate", scientists reported-likely melting only in the last three years. The glacier has retreated at a steady rate of about 0.4 to 0.5 miles (0.6 to 0.8 km) annually since 1992, the researchers found.

The glacier isn't retreating uniformly. Despite this stable rate of grounding-line retreat, the melt rate on this side of the glacier is extremely high.

The complex pattern the new readings reveal - which don't fit with current ice sheet or ocean models - suggest scientists have more to learn about how water and ice interact with one another in the frigid but warming Antarctic environment.

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