The Thwaites Glacier in Antarctica — nicknamed the “Doomsday Glacier” because of its potential to unleash cataclysmic sea-level rise around the globe — is melting quickly and in unexpected ways, new research shows.
The glacier is the most vulnerable one on the entire continent of Antarctica. Its collapse would trigger a catastrophic event that could directly cause global sea level rise of more than two feet — enough to overwhelm many coastal communities. It could also pull down surrounding glaciers as it crumbles, which would cause seas to rise by up to 10 feet — an amount that would completely redraw coastlines around the world put millions of people at risk. Researchers have known for decades that it’s unstable.
Part of what holds the glacier in place is an ice shelf that juts out onto the surface of the ocean. Deploying an underwater robot beneath that 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 for long-term sea-level rise.
The researchers said that overall 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 was occurring in unexpected places.
The findings do not alter the fact that the Thwaites is among the fastest receding and least stable ice shelves in Antarctica, and of the most concern when it comes to sea level rise. It also does not change forecasts that the collapse of the shelf and the glacier it is part of would lead to about 2 feet of rise over several centuries.
The research “is telling us a lot more about the processes that drive retreat on Thwaites,” said one of the scientists, Peter E.D. Davis, an oceanographer with the British Antarctic Survey.
The new findings were in two papers in Nature: Davis was the lead author of one, and Britney E. Schmidt, a geophysicist at Cornell University, was the lead author of the other.
The researchers camped on the ice during the Antarctic summer of 2019-20, and used hot water to bore 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 carried cameras, sonar and thrusters for propulsion. Schmidt slowly “drove” the device via a long tether.
Icefin explored crevasses and steep-sided terraces on the underside of the ice, and found rapid melting there, as the near-vertical orientation of the sidewalls allowed mixing and brought more heat to bear on the ice.
Like Davis, Schmidt said that the findings provided important context for what is happening at the Thwaites glacier. “It’s not ‘warm water equals X amount of melting,’” she said. “It’s ‘warm water plus process X means melting.’”
Because overall there is less melting on the underside but the Thwaites is still unstable, she said, “it means it actually takes 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.