Gigantic cavity in Antarctic glacier indicates rapid decay due to climate change: NASA

NASA scientists have discovered a gigantic cavity, almost 300 metres tall, growing at bottom of Thwaites Glacier in West Antarctica, indicating rapid decay of ice sheet and acceleration in global sea levels due to climate change.

findings, published in journal Science vances, highlight need for detailed observations of Antarctic glaciers' undersides in calculating how fast sea levels will rise in response to warming.

Researchers expected to find some gaps between ice and bedrock at Thwaites' bottom where ocean water could flow in and melt glacier from below, NASA said in a statement.

size and explosive growth rate of newfound hole, however, surprised m.

It is big eugh to have contained 14 billion tonnes of ice, and most of that ice melted over last three years.

"We have suspected for years that Thwaites was t tightly attached to bedrock beneath it," said Eric Rigt of University of California, Irvine in US.

"Thanks to a new generation of satellites, we can finally see detail," said Rigt, who is also associated with NASA's Jet Propulsion Laboratory (JPL).

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cavity was revealed by ice-penetrating rar in NASA's Operation IceBridge, an airborne campaign beginning in 2010 that studies connections between polar regions and global climate.

researchers also used data from a constellation of Italian and German -borne syntic aperture rars.

se very high-resolution data can be processed by a technique called rar interferometry to reveal how ground surface below has moved between ims.

"( size of) a cavity under a glacier plays an important role in melting. As more heat and water get under glacier, it melts faster," said Pietro Milillo of JPL.

Thwaites Glacier is currently responsible for about four per cent of global sea level rise, researchers said.

It holds eugh ice to raise world ocean a little over 65 centimeters and backstops neighbouring glaciers that would raise sea levels an ditional 2.4 metres if all ice were lost, y said.

"We are discovering different mechanisms of retreat," Millilo said.

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Different processes at various parts of 160-kilometer-long front of glacier are putting rates of grounding-line retreat and of ice loss out of sync, NASA said.

huge cavity is under main trunk of glacier on its western side -- side farr from West Antarctic Peninsula.

In this region, as tide rises and falls, grounding line retreats and vances across a zone of about three to five kilometers.

glacier has been coming unstuck from a ridge in bedrock at a stey rate of about 0.6 to 0.8 kilometers a year since 1992.

Despite this stable rate of grounding-line retreat, melt rate on this side of glacier is extremely high.

"On eastern side of glacier, grounding-line retreat proceeds through small channels, maybe a kilometer wide, like fingers reaching beneath glacier to melt it from below," Milillo said.

In that region, rate of grounding-line retreat doubled from about 0.6 kilometers a year from 1992 to 2011 to 1.2 kilometers a year from 2011 to 2017, researchers said.

Even with this accelerating retreat, however, melt rates on this side of glacier are lower than on western side, y said.