Huge cavity, 40 square kilometers and 300 feet tall, is growing at the bottom of the Thwaites glacier in West Antarctica and confirms that mass of ice breaks.
It also highlights the need for detailed observations of the lower part of the Antarctic glaciers in order to calculate how fast global levels must increase in response to climate change.
Researchers hoped to find some gaps between the ice and rocks at Thwaites' foot, where ocean water could flow and melt the glaze from below.
However, the size and explosive growth rate of the new holes surprised them. It's big enough to keep 14 billion tons of ice, and most of the ice has dissolved in the last three years.
"For years we have suspected that Thwaites are not well-tied to rocks below the surface," said Eric Rignot of the University of California, Irvine, and NASA's Jet Propulsion Laboratory (JPL). Rignot is a co-author of a new study, which
"Thanks to the new generation of satellites, we can finally see the details," he said.
The cavity was discovered by ice-breaking radars in NASA's IceBridge Operation, an air campaign that began in 2010 and explores links between polar regions and the global climate.
Researchers also used data from the constellation of radar synthetic apertures from Italian and German aircraft. High resolution data can be processed by a technique known as radar interferometry to reveal how the surface underneath the earth moves between images.
"[El tamaño de] The cavity beneath the glacier plays an important role in the melt, "says lead author of the study, Pietro Milillo of JPL." As more heat and water penetrate the glacier, it's faster to melt, "he said.
Numerical models of ice sheets use a fixed form for introducing a cavity beneath the ice instead of changing the cavity. The new discovery implies that this limitation probably makes these models underestimate how quickly Thwaites loses ice.
Glacial Thwaites, the size of the state of Florida, USA, is currently responsible for approximately 4 percent of sea level rise in the world. It has enough ice to lift the world's ocean a little over two centimeters and keep the neighboring glaciers, which would raise the sea level by 2.4 centimeters if all the ice was lost.
Thwaites is one of the most difficult places on Earth but will be better known than ever. The United States's National Foundation for Science and the United Nations Environmental Research Council set up a five-year field project to address the most critical issues about their processes and characteristics. International co-operation with Thwaites will begin its field trials in the summer of the South Hemisphere 2019-20.
The large cavity lies beneath the main jumble of the glacier on the west side, the farthest side of the Western Antarctic Peninsula. In this region, as the tide rises and falls, the earthing line retreats and advances through an area of approximately 3 to 5 kilometers.
Since 1992, the glacier has been separated from rock cliffs at a constant speed of about 0.6 to 0.8 kilometers per year. Despite a stable landing line rate, the rate of fusion on this side of the glacier is extremely high.