Scientists in west Antarctica have captured a first-of-its-kind seafloor mapping near the world’s widest glacier – which is shrinking at a pace that could one day raise global sea levels up to 10 feet, according to the University of South Florida.
U.S., U.K. and Swedish researchers deployed underwater robots close to the seafloor of the Thwaites Glacier to retrieve data, said Dr. Alastair Graham, a geological oceanography associate professor at the University of South Florida. Graham led the study released Monday.
“We've essentially found Thwaites has a speed limit that's higher than what we expected it to have,” Graham told USA TODAY. Experts say what they've learned about its ability to quickly retreat raises concerns for the future.
The major concern with the Thwaites Glacier, also nicknamed the "Doomsday Glacier," is its size: The approximately 70,000-square-mile glacier is as big as Florida, according to Graham. Researchers in June said the glacier may be losing ice at its fastest pace in the past 5,000 years, according to the International Thwaites Glacier Collaboration.
“It locks up so much sea level in that one glacial system that we can't not focus attention on it because it's critical to how we view our shorelines,” Graham said. “Thwaites has the potential to rewrite our coastlines for everybody on the planet.”
Here's what to know about the retreating Thwaites Glacier.
What did the robots reveal about the Thwaites Glacier?
The Thwaites Glacier has been on scientists’ radar for at least 30 years, Graham said, but its recent thinning and accelerated melting speed made it a focus more recently.
“It's actually melting probably from beneath, mostly on the ocean side,” Graham said. “It's speeding up, so the amount of ice that is coming out into the ocean – a bit like a conveyor belt – is getting faster, and it's also shrinking inland.”
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Robots captured high-resolution images of the seabed just under half a mile underwater in front of the glacier. The images showed traces of where Thwaites left imprints of where it once sat. Scientists will use the more than 160 parallel ridges – described as riblike formations – to examine Thwaites’ historical activity and make predictions about its future possible movement, according to Graham.
One particular seafloor area showed Thwaites retreated over a six-month period, though Graham said it’s not clear when it happened.
“(It could have been) maybe 200 years ago, or maybe even more recently in the mid-20th century, so the 1940s or 1950s when we weren't even watching Thwaites,” Graham said. “But it was going back at a rate that’s at least twice what it’s retreating at right now."
There's a high chance of a repeat occurrence, Graham noted.
"It's highly likely that in the future, we'll see these kind of events happening again, a really quick retreat where there is a lot of ice going into the ocean very quickly," he said.
Why is the Thwaites Glacier unstable?
Thwaites is one of Antarctica’s most unstable glaciers, according to the International Thwaites Glacier Collaboration. It sits on bedrock far below sea level, and the rock slope deepens farther into Antarctica’s interior, according to Graham.
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“That's a situation that we know from basic glaciological theory leads to an unstable configuration,” Graham said. “As you retreat the ice into the interior of Antarctica, it opens up more thickness of ice to be exposed to the ocean and lost, so it's kind of like a runaway system, where you lose more and more and more over time."
Why is it called the 'Doomsday Glacier'?
The term originated from a journalist that joined research groups in Antarctica, according to Ted Scambos, a principal investigator for the International Thwaites Glacier Collaboration’s Science Coordination Office.
Thwaites is retreating at an accelerated pace by glacial standards as a result of climate change, Scambos said, who called it a “very slow-moving disaster.”
“I'm not wild about the ‘Doomsday Glacier’ moniker because it does make it sound like it's hopeless, and it makes it sound like it will happen very suddenly,” Scambos told USA TODAY.
Graham agreed that the “Doomsday Glacier” nickname is inaccurate.
“It gives this impression of annihilation that we're going to be basically wiped out overnight, and I think that's not the case at all,” Graham said.
It may be one or two generations, or “multiple decades,” before Thwaites loses a significant amount of ice, according to Graham. He added scientists might see changes in the glacier’s ice shelf, the floating part in front of the glacier, within the next five to 10 years.
What happens if the Thwaites Glacier collapses?
Thwaites and some nearby glaciers experience a net loss of about 50 million tons of ice annually, Scambos said.
“We think that it's very upwardly mobile, because it's on the verge of retreating into some fairly deep areas in the interior of West Antarctica,” he said.
If the massive glacier’s ice melted, it would have a global impact, according to Graham. “Every coast, every nation with a coastline would see the effects of Thwaites losing all its ice to the ocean,” he said.
The resulting sea level rise wouldn’t affect all coastlines equally, Scambos explained.
“It's not like filling up a bathtub, where everything rises evenly.” he said. Locations farther away from Thwaites, like the tropics, would see higher sea level rise than areas closer to where Thwaites is losing ice, according to Scambos.
“In fact, right where the coast is losing a lot of ice, the sea level actually drops because of a tremendous loss of mass of the ice,” said Scambos, who added that as the ice sheet shrinks, it doesn’t hold the ocean to it anymore.
“There's so much mass leaving Antarctica, and Greenland too, for that matter, that it no longer pulls the ocean close to it the way it used to, so as this ice flows into the ocean, the ocean is also not so strongly held against the coast of Antarctica,” he said.
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