Part of what keeps the glacier in place is a glacier that protrudes onto the surface of the ocean. By deploying an underwater robot beneath the rapidly melting ice shelf, scientists have uncovered new clues about how it is melting. The findings will help assess the threat it and other ice shelves pose to long-term sea level rise.
The researchers said the total melting of the underside of part of the shelf was less than expected from estimates derived from computer models. But they also discovered that rapid melting occurred in unexpected places.
The findings do not change the fact that the Thwaites are among the fastest retreating and least stable ice shelves in Antarctica, and of greatest concern when it comes to sea level rise. Nor does it change forecasts that the collapse of the shelf and the glacier it is a part of would lead to about 2 feet of rise over several centuries.
The research “tells us a lot more about the processes driving retreat at Thwaites,” said one of the researchers, Peter ED Davis, an oceanographer at the British Antarctic Survey.
The new findings were in two papers in Nature: Davis was lead author of one, and Britney E. Schmidt, a geophysicist at Cornell University, was lead author of the other.
The researchers camped on the ice during the 2019-20 Antarctic summer, using warm water to drill several holes through 2,000 feet of ice to the ocean below.
The star of the show was the underwater robot, called Icefin. A cylinder 9 inches in diameter and about 12 feet long, it had cameras, sonar and thrusters for propulsion. Schmidt slowly “drove” the device via a long tether.
Icefin explored crevasses and steep terraces on the underside of the ice, and found rapid melting there, as the nearly vertical orientation of the sidewalls allowed mixing and brought more heat to the ice.
Like Davis, Schmidt said the findings provided important context for what’s happening at Thwaites Glacier. “It’s not ‘hot water equals X amount of melting,'” she said. “It’s ‘hot water plus process X means melting.’
Because overall there is less melting on the underside, but the Thwaites are still unstable, she said, “that means it’s actually taking a lot less than we thought to push these things out of balance.”
Material from The New York Times wire service was used in this report.
Dharna Noor can be reached at firstname.lastname@example.org. Follow her on Twitter @dharnanoor.