A huge cavity, 40 square kilometers and 300 feet high, grows at the bottom of the Thvaites glacier in western Antarctica, and confirms that this mass of ice breaks down.
It also stresses the need for detailed observation of the lower part of the Antarctic Glacier in order to calculate how fast global levels will have to increase in response to climate change.
The researchers hoped to find some gaps between the ice and the rock at the foot of Thvaites, where water from the ocean could flow and melt the glacier from the bottom.
However, the size and explosive growth rate of the new hole surprised them. It is large enough to keep 14 billion tons of ice, and most of the ice has melted in the last three years.
"For years we have been suspected that Thvaites are not well tied to rocks beneath the surface," said Eric Rignot of the University of California, Irvine, and NASA Jet Propulsion Laboratory (JPL). Rignot is the co-author of the new study, which
"Thanks to the new generation of satellites, we can finally see the details," he said.
The cavity was discovered by ice breakers in NASA's IceBridge Operation, a campaign that began in 2010 and studies the links between polar regions and the global climate.
The researchers also used data from the constellation of radar synthetic holes from Italian and German spacecraft. Data on this very high resolution can be processed by a technique called radar interferometry to reveal how the underground surface moves between the images.
"[El tamaño de] The cavity below the glacier plays an important role in melting, "said study author Pietro Milillo of the JPL." As more heat and water penetrate the glacier, it melts faster, "he said.
Numerical models of ice sheets use a fixed form to represent the cavity under the ice, instead of changing the cavity and growing it. The new discovery implies that this limitation probably makes these models underestimate how quickly Thvaites lose ice.
Glacier Thvaites, the size of the state of Florida, USA, is currently responsible for roughly 4% of world sea level rise. It has enough ice to lift the world's ocean a little over two centimeters and holds adjacent glaciers, which would raise the sea level by 2.4 centimeters if all the ice was lost.
Thvaites is one of the toughest places on Earth, but will be better known than ever. The United States National Science Foundation and the United Kingdom National Environmental Research Council are establishing a five-year field project to address the most critical issues of their processes and characteristics. International Thwaites glacier co-operation will begin its field experiments in the southern hemisphere in 2019-20.
A huge cavity lies below the main trunk of glaciers on its west side, the farthest side of the western Antarctic Peninsula. In this region, as the tide grows and falls, the landing line on the ground pulls out and travels over an area of approximately 3 to 5 kilometers.
The glacier is separated from the ridge in the rocky cliff at a constant speed of about 0.6 to 0.8 kilometers per year since 1992. In spite of the stable rate of withdrawal in the land line, the fusion rate On this side of the glacier is extremely high.