Skinny robot documents the forces eroding glacier
Scientists got their first up-close look at what’s eating away part of Antarctica’s Thwaites ice shelf, nicknamed the Doomsday Glacier because of its massive melt and sea rise potential, and it’s both good and bad news.
Using a 13-foot pencilshaped robot that swam under the grounding line where ice first juts over the sea, scientists saw a shimmery critical point in Thwaites’ chaotic breakup, “where it’s melting so quickly there, there’s just material streaming out of the glacier,” said robot creator and polar scientist Britney Schmidt of Cornell University.
Before, scientists had no observations from this critical but hard-to-reach point on Thwaites. But with the robot named Icefin lowered down a slender 1,925foot hole, they saw how important crevasses are in the fracturing of the ice, which takes the heaviest toll on the glacier, even more than melting.
“That’s how the glacier is falling apart. It’s not thinning and going away. It shatters,” said Schmidt, lead author of one of two studies in Wednesday’s journal Nature.
That fracturing “potentially accelerates the overall demise of that ice shelf,” said Paul Cutler, the Thwaites program director for the National Science Foundation who returned from the ice last week. “It’s eventual mode of failure may be through falling apart.”
The work comes out of a $50 million multi-year international research effort to better understand the widest glacier in the world.
The Florida-sized glacier has gotten its nickname because of how much ice it has and how much seas could rise if it all melts: more than 2 feet, though that’s expected take hundreds of years.
The melting of Thwaites is dominated by what’s happening underneath, where warmer water nibbles at the bottom, something called basal melting, said Peter Davis, an oceanographer at British Antarctic Survey who is a lead author of one of the studies.
“Thwaites is a rapidly changing system, much more rapidly changing than when we started this work five years ago and even since we were in the field three years ago,” said Oregon State University ice researcher Erin Pettit, who wasn’t part of either study. “I am definitely expecting the rapid change to continue and accelerate over the next few years.”
The good news: Much of the flat underwater area they explored is melting much slower than they expected. The bad news: That doesn’t really change how much ice is coming off the land part of the glacier and driving up sea levels, Davis said.
Davis said the melting isn’t nearly the problem at Thwaites that glacier retreat is. The more the glacier breaks up or retreats, the more ice floats in water. When ice is on ground as part of the glacier it isn’t part of sea rise, but when it breaks off land and then goes onto water it adds to the overall water level by displacement, just as ice added to a glass of water raises water level.