Saturday, 23 February, 2019

Radar analysis: researchers find giant cavity in Antarctic glacier

Theresa Hayes | 05 February, 2019, 02:40

Their findings show that Thwaites Glacier is suffering from extensive ice thinning, receding, and calving, as well as a 300-meter (1,000-foot) hole inside its west wing that's growing at an "explosive" rate.

The cavity is two-thirds the size of Manhattan. The cavity was once filled with approximately 14 billion tons of ice and the huge amount melted in less than 3 years. The size and the extremely fast growth of the cavity is surprised but then they.

"We have for years suspected that Thwaites is not firmly connected to the substrate", says Co-author Eric Rignot.

"Thanks to a new generation of satellites, we can finally see the detail". Researchers combined the NASA data with data from Italian and German spaceborne synthetic aperture radars.

These very high-resolution data can be processed by a technique called radar interferometry to reveal how the ground surface below has moved between images.

"[The size of] a cavity under a glacier plays an important role in melting", lead author Pietro Milillo, from NASA's Jet Propulsion Laboratory, said in a statement. Researchers on the project say that they expected to find some gaps between ice and bedrock at the bottom of the glacier where ocean water can flow in and melt the glacier from below.

According to a study by NASA, the void was caused by newly discovered "fingers" of warm water flowing into cracks in the glacier caused by mounting climate change. Thwaites Glacier, among the most threatened hunks of ice on the continent, is in even more dire straits than previously reported.

This would inundate coastal cities like NY, which could probably cope with the changes if they were gradual but would be seriously and potentially mortally damaged if sea levels rose too quickly for engineers to mount a response. Thwaites also serves as a backstop to other Antarctic glaciers-if they subsequently collapsed, sea levels could rise by another eight feet. With climate change likely to continue accelerating this melt, the implications for global sea level rise are considerable.

Thwaites Glacier is located in West Antarctica, an area that is facing what could be runaway melt owing to geography and inescapable heat.

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

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.