It's OK to be nervous about the Thwaites Glacier.
If this Florida-sized Antarctic glacier collapsed, it could ultimately unleash enough ice to boost sea levels by ten feet. Thwaites is already dumping "huge amounts of ice into the ocean," and in 2019, Antarctic researchers located a cavity two-thirds the size of Manhattan near the bottom of Thwaites.
And it's here, at the bottom, where Thwaites' destiny lies.
Where this colossal river of ice extends out from Antarctica and meets the seafloor is called the "grounding line." This point acts like a plug, holding Thwaites back so bounties of ice on land can't flow unimpeded into the sea, raising sea levels.
For the first time, researchers journeyed to the profoundly remote Antarctic to drill down 2,300 feet — all the way through mighty Thwaites. This allowed them to drop down a robot, Icefin, to capture eerie footage of Thwaites' critical grounding zone.
"We designed Icefin to be able to access the grounding zones of glaciers, places where observations have been nearly impossible, but where rapid change is taking place," Britney Schmidt, Icefin's lead scientist, said in a statement. "To have the chance to do this at Thwaites Glacier, which is such a critical hinge point in West Antarctica, is a dream come true for me and my team."
"We’ve taken the first close-up look at a grounding zone," she added. "It’s our ‘walking on the moon’ moment."
After lowering Icefin nearly half a mile down the drilled hole, scientists remotely guided the long, cylindrical, yellow robot over a mile to the grounding zone, where relatively warm waters are eating away at Thwaites' bottom. In the video above, you can glimpse Thwaites' icy ceiling through the murky water as fish dash by the camera.
Icefin also captured images of both parts of the grounding zone and the rocky seafloor below, separated by about a meter of water:
Icefin took the temperature down there, too. The saltwater measured two degrees above freezing, David Holland, a New York University glaciologist on the mission, told The Washington Post.
"That is really, really bad," Holland said. "That’s not a sustainable situation for that glacier."
When might Thwaites break from its grounding line? It's a question Antarctic scientists are vigilantly investigating. In the last thirty years, the amount of ice flowing from Thwaites and nearby destabilized glaciers in West Antarctica has doubled.
