09 FEB 2020
Researchers have taken the first-ever images of the Thwaites Glacier in Antarctica, a glacier about the size of Florida that is anticipated to play a key role in future sea level rise.
The images, taken by a robotic underwater vehicle, were part of a broad set of data collected in a variety of experiments by the International Thwaites Glacier Collaboration.
Already, Thwaites accounts for about four percent of global sea-level rise. Researchers have had concerns that a tipping point in the stability at its foundations could result in a run-away collapse of the glacier and boost sea levels by as much as 25 inches.
The area of concern that the underwater vehicle visited is called the grounding line, and it is important to the stability of Thwaites Glacier’s footing. It is the line between where the glacier rests on the ocean bed and where it floats over water. The farther back the grounding line recedes, the faster the ice can flow into the sea, pushing up sea-level.
“Visiting the grounding line is one of the reasons work like this is important because we can drive right up to it and actually measure where it is,” said Britney Schmidt, an ITGC co-investigator from the Georgia Institute of Technology. “It’s the first time anyone has done that or has ever even seen the grounding zone of a major glacier under the water, and that’s the place where the greatest degree of melting and destabilization can occur.”
The underwater robot, Icefin, was engineered by Schmidt’s Georgia Tech lab. The Georgia Tech team was part of a greater collaboration between researchers from the U.S. and the British Antarctic Survey (BAS). A BAS hot water drill melted a hole 590 meters deep (1,935 feet) to access the ocean cavity for Icefin.
“Icefin swam over 15 km (9.3 miles) round trip during five missions. This included two passes up to the grounding zone, including one where we got as close as we physically could to the place where the seafloor meets the ice,” said Schmidt. “We saw amazing ice interactions driven by sediments at the line and from the rapid melting from warm ocean water.”
Over the past 30 years, the amount of ice flowing to the sea from Thwaites and its neighboring glaciers has nearly doubled. “While Greenland’s contribution to sea level has already reached an alarming rate, Antarctica is just now picking up its contributions to sea level,” Schmidt said. “It has the largest body of ice on Earth and will contribute more and more of sea-level rise over the next 100 years and beyond. It’s a massive source of uncertainty in the climate system.”
