January 31, 2019 – 16:47
The size of Thwaites is similar to the state of Florida, and its mass contains 14,000 million tons of ice. Its decomposition could increase the ocean level by two centimeters.
As it is responsible for rising sea levels, it is considered to be the most dangerous glacier in the world. And now, a new investigation creates a warning. The giant cavity, 40 square kilometers and 300 meters high, which grows at the bottom of Thwaites Glacier in West Antarctica, confirms that this ice mass has broken down.
The results of a new study by NASA show the need for detailed observations on the bottom of the Antarctic glaciers to calculate how fast the global sea level will rise in response to climate change.
The researchers hoped to find some gaps between the ice and the rocks at the bottom of Thwaites, where ocean water could flow and melt the glacier from below. The size of the new hole and the explosive growth rate surprised them. It is big enough to hold 14 billion tons of ice, and most of this ice has melted over the last three years.
"Below the glacier is an important part of the composition," said the leading author of the study, Pietro Milillo, NASA Jet Propulsion Laboratory (JPL). they enter the glacier, it melts faster. "
"For years, we have thought that Thwaites was not well attached to an existing rock," said the University of California and JPL. Rignot is the author of a new study published by Science Advances. "Thanks to the new generation of satellites, we can finally see the details," he said.
The cavity was discovered by the ice penetration radar NASA in IceBridge, launched in 2010 and exploring the link between polar regions and the global climate. The researchers also used data from the synthetic aperture radar constellation of Italian and German spacecraft. These very high resolution data can be processed by a technique called radar interferometry to discover how the earth's surface below has moved between images.
Thwaites is one of the most difficult places to reach on Earth, but it is closer than ever. The US National Science Foundation and the UK National Environmental Research Council set up a five-year rural project to answer the most important questions about their processes and qualities. International Thwaites Glacier Collaboration will begin field experiments in the next southern hemisphere during the summer.
The state of Florida, the Thwaites Glacier, is currently responsible for about 4% of the sea level rise worldwide. It has enough ice to enlarge the world's ocean just over 2 centimeters and hold adjacent glaciers that would raise the sea level by 2.4 centimeters if all the ice were lost.
The huge cavity is located below the glacial main frame on the western side, furthest from the western Antarctic Peninsula. In this region, when the floods rise and fall, the land connection line departs and moves through an area of about 3 to 5 kilometers. From 1992, the glacier was separated from the base of the bedrock at a constant speed of about 0.6 to 0.8 kilometers per year. Despite this steady retreat speed on the land line, the speed of fusion is very high on this glacier side.
The numerical models of the sheets use a fixed form to depict the cavity under the ice rather than allowing the cavity to change and grow. The new discovery means that this limitation will probably lead to an underestimation of these models, how quickly Thwaites loses ice.