A robot submarine has returned from the dark lower abdomen of one of Antarctica’s biggest glaciers with cold news – it can melt faster than we previously thought.
Thwaites Glacier, a giant ice shelf in West Antarctica, has been on the radar of climate scientists for two decades now. But they did not know how fast the glacier was melting and how close it was to completing the collapse, until researchers sent an unmanned submarine under the ice shelf.
The first measurements ever taken in the dark waters below the 19,000 square kilometers of ice revealed disturbing information: A previously underestimated stream of hot water is flowing from the east and bouncing away at a number of important “fixed points” ” anchor the shelf to the land.
Related: Time lapse images of retreating glaciers
“Our observations show that hot water is rushing from all sides at bottlenecks critical to ice shelf stability, a scenario that could lead to loosening and retreat,” the study authors wrote in the April 9 issue of the journal. . Scientific progress. In other words, the entire ice shelf can become detached and then flow to the ocean.
As one of Antarctica’s fastest melting glaciers, the Thwaites Glacier, nicknamed “Doomsday Glacier”, has lost an estimated 595 billion tons (540 billion tons) of ice since the 1980s, contributing annually to ‘ an increase in global sea levels of 4%. The glacier acts like a cork in a wine bottle, preventing the rest of the ice in the region from flowing into the sea, so that the collapse of the Thwaites Glacier could potentially cause the rest of the West Antarctic ice sheet, which can lead up to 10 feet (3 meters) rising in world sea level.
“The concern is that this water comes in direct contact with the bottom of the ice shelf at the point where the ice tongue and the shallow seabed meet,” studied co-author Alastair Graham, an associate professor of geological oceanography at the University of South Florida. , told Gizmodo.
This is terrible news for the glacier.
“This is the last fortress for Thwaites, and as soon as it opens up in front of the seabed, there is nothing else that can hold the ice shelf. The hot water probably also mixes in and around the baseline, deep in the cavity, and it “means that the glacier is also attacked at its feet where it rests on solid rock,” Graham told Gizmodo.
Thwaites is located more than 1,600 kilometers from the nearest research base, even by Antarctic standards. Scientists have previously tested temperatures and even equilibrium drop a torpedo-shaped robot through a hole 700 meters deep in the ice, but this study is the first time a submarine has penetrated the cavity under the shelf. The rig, named Ran after the Norwegian goddess of the sea, measured the strength, temperature, oxygen content and salinity of the ocean currents flowing under the glacier.
Sonar on the ship also enabled a high-resolution mapping of the cavity floor, which helped scientists visualize the roads that take in and take out currents. They noticed three main inflows of water. One, a deep-water flow from the east, was once assumed to be blocked by an underwater reef, but Ran’s data show that the current is moving into the bay. This means that currents flow from both sides to the glacier and possibly erode at the main anchorage point in the north.
How much melting is going on is not clear, but the researchers predict that just one of the streams alone could reduce the ice by more than 85 gigatons a year.
The findings are not the only worrying recent news that has come from West Antarctica. Exposure to warmer water could also push the neighboring Pine Island glacier past a tipping point, researchers showed in a study published in the Journal on March 25. The Cryosphere. According to the Cryosphere study, the Thwaites and Pine Island glaciers are currently responsible for 10% of the continuous increase in global sea levels.
“The good news is that we are now, for the first time, collecting data needed to model the dynamics of the Thwaites Glacier,” studied lead author Anna Wåhlin, professor of oceanography at the University of Gothenburg in Sweden. said in a statement. “These data will help us better calculate ice melting in the future. Using new technology, we can improve the models and reduce the great uncertainty that currently prevails over global sea level variations.”
Originally published on Live Science.