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For the first time, scientists have taken a close look at what is eroding part of Antarctica’s Thwaites Ice Shelf, nicknamed the doomsday glacier for its enormous potential for melting and sea level rise, and it’s both good and bad news .
Scientists using a 13-foot-long pencil-shaped robot to swim below the grounding line where the ice first sticks out of the sea saw a sparkling tipping point in Thwaites’ chaotic rupture, “where it melts so fast that only matter outflow glaciers,” said Britney Schmidt, a robot creator and polar scientist at Cornell University.
Previously, scientists had not observed from this critical but inaccessible point on Thwaites. But as a robot named Icefin drilled into the 1,925-foot (587-meter) slender hole, they saw the importance of cracks in ice calving, which does the most damage to glaciers, even more than melting. “That’s how a glacier collapses. It doesn’t thin and disappear. It crumbles,” said Schmidt, lead author of one of two studies published Wednesday in the journal Nature.
Such ruptures “could hasten the overall demise of the ice shelf,” said Paul Cutler, director of the National Science Foundation’s Thwaites Program, who returned from the ice last week. “Its ultimate failure mode could be falling apart.”
The work is the result of a multi-year, $50 million international research effort to better understand the world’s widest glacier. The Florida-sized glacier has earned the nickname the “Apocalyptic Glacier” because of how much ice it has and how much sea levels would rise if it all melted more than 2 feet (65 centimeters), though that’s expected to take hundreds of years.
Oceanographer Peter Davies of the British Antarctic Survey, lead author of one of the studies, said melting in the Thwaites Islands was largely influenced by what was happening in the subsurface, with warm water eating away at the bottom, known as basal melt.
“Thwaites is a rapidly changing system, changing more rapidly than when we started this work five years ago, or even when we entered the field three years ago,” said Erin Pettit, an ice researcher at Oregon State University in the study. “I definitely expect this rapid change to continue and accelerate over the next few years.”
Richard Ailey, a glaciologist at Penn State University, who was also not involved in the study, said the new work “gives us an important insight into the processes that affect fractures that could eventually rupture and cause most ice shelves to disappear.”
The good news: Most of the flat underwater areas they explored were melting much more slowly than they expected. The bad news: That doesn’t really change the amount of ice that’s breaking off the land-based portion of the glacier and pushing up sea levels, Davis said.
Glacier retreat is hardly Thwaites’ problem, Davis said. The more the glacier breaks up or retreats, the more ice floats in the water. When ice is on the ground as part of a glacier, it is not part of sea level rise, but when it breaks off land and then enters the water, it increases the overall water level through displacement, just like adding ice to a glass of water raises the water level .
There’s more bad news: it’s coming from a larger, more stable area east of Thwaites. The researchers couldn’t land the plane safely and drill a hole through the ice in the main stem, which breaks down much faster. They also found stepped steps in parts of the more stable east side, where the cracks were faster and deeper.
The key to understanding exactly how bad conditions are on the glacier requires going to the main trunk and watching the melt from below. But that would require a helicopter rather than a heavier plane to land on the ice, and it would be very difficult, said study co-author Eric Rignot of the University of California, Irvine.
The main glacier’s surface is so jumbled up with crevasses that it almost looks like a set of sugar cubes. NSF’s Cutler said there was no place for the plane to land.
Ted Scambos of the National Snow and Ice Data Center, who was not involved in the study, said the findings help to understand how Thwaites declined.
“Unfortunately, this will remain a significant problem a century from now,” Scambos said in an email. “But our better understanding gives us time to act to slow the rate of sea level rise.”
As the scrawny robot moves through holes in the ice (holes created by jets of hot water), the cameras show not only meltwater, but key crevasses and the sea floor. It shows small animals, especially sea anemones, swimming under the ice.
“It’s really, really cool to stumble upon them in this environment,” Schmidt said in an interview. “We’re so exhausted that you sort of wonder, ‘Am I really seeing what I’m seeing?'” You know, because there are these creepy little aliens (anemones) hanging out on the ice sea interface.
“In the background, all these sparkling stars like rocks and sediment and things picked up from glaciers,” Schmidt said. ‘And then there were sea anemones. It really is a crazy experience.
(Disclaimer: This story was auto-generated from a syndicate feed; only images and captions may have been edited by www.republicworld.com)
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