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Home / Science / A submarine emerges from under a failing glacier to measure the rising sea

A submarine emerges from under a failing glacier to measure the rising sea



Oceanographer Anna Wåhlin walked across the bridge of the Nathaniel B. Palmer icebreaker like a nervous parent waiting for a teenager to curfew.

The fiery-orange submarine she named Ran after the Norse goddess of the sea had no chance yet of his first mission in the water depths around the Thwaites Glacier of West Antarctic.

"She's a very spirited woman," Wåhlin said about the $ 3.6 million unmanned submarine as she peered through her binoculars in a cloudy day in March.

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This story was released with PRI's The World, the award-winning public radio program and the podcast on global topics, news and insights from the BBC, WGBH, PRI and PRX.

Ran was too late. Wåhlin was not worried about the disappearance of the submarine, but it was Ran's first season in polar waters, and there were a number of kinks that needed to be compensated.

Oceanographer Anna Wåhlin, Director of the Hugin Project, is waiting on the bridge of Nathaniel B. Palmer for the Hugin Submarine, which appears in icy waters near the Thwaites Glacier.

Carolyn Beeler / The World

Wåhlin, an oceanographer at the Swedish University of Gothenburg, was one of about two dozen scientists from A pioneering scientific expedition to Thwaites Glacier last winter. The two-month cruise aboard the Palmer marked the beginning of a five-year, $ 50 million international collaboration to better understand the situation of the Thwaites. Scientists believe that the massive glacier is about to collapse, but how fast that could happen remains open.

Florida's Thwaites Glacier holds enough ice to raise global sea levels by two feet. If the glacier collapses, it could destabilize part of the West Antarctic, raising sea levels by about 1.80 meters.

This would mean a disaster for coastal cities from Miami to Mumbai that would be flooded by floods. [19659003] Ground Zero for this slow catastrophe is the edge of the glacier, where land-based ice sticks out into the Amundsen Sea. Warm water is believed to melt the underside of this 75-mile ice shelf, but the area is as mysterious as it is momentous.

"We know more about the moon than about that particular part of the earth," Wåhlin said.

Scientists believe that changing wind patterns drive a lot of warm water, called circumpolar deep water, from the deep ocean to the continental shelf off Antarctica and Thwaites. But there has never been a scientific instrument under the ice shelf to investigate.

The hugin nicknamed Ran cost approximately $ 3.6 million.

Linda Welzenbach / Rice University

That's why Wåhlin worked for seven years to get a Hugin submarine, a 25-foot, torpedo-shaped, autonomous underwater vehicle with oceanographic sensors.

"This was the dream, Thwaites and the West Antarctic ice shelf," Wåhlin said. "We did that when we applied for the money. We said that this is the only way to do research under floating ice shelves. "

Thanks to the advances in satellite imagery in recent decades, scientists can estimate how much ice Thwaites is losing – nearly 80 gigatons per year, an increase of six 25 years ago.

But predicting future melt rates and predicting whether Thwaites will trigger a runaway collapse is almost impossible without data on the ground.

"We are not sure yet what the Black Swan is" The worst thing that can happen in Thwaites, "said Richard Alley, a Penn State University glaciologist.

Two widely cited model studies published in recent years (here and here) suggest a complete collapse of the West Antarctic ice sheet could come within 250 years. Alley warns, however, that this should not be a "worst case" scenario.

"We are very confident that this five-year research collaboration will give us a lot of insight," Alley said.

Before Never before has a ship sailed into the fast flowing central part of Thwaites. The scientists had never measured the warm water directly in front of the glacier. So they did not know how fast she was flowing, how far she reached under the ice shelf or how thick the ice was.

The small orange autonomous submarine, paired with sonar equipment and oceanographic instruments based on the larger 300-foot research vessel, will begin to answer these questions.

He completed his first test mission of the Magellan Strait Expedition on 1 February 2019.

Linda Welzenbach / Rice University

Wåhlin's "wayward child"

The factory name for the submarine built in Kongsberg is Hugin, but Wåhlin is only the third woman in Sweden who has earned a doctorate in oceanography. Ran dubbed it after the Norse goddess as "a small stimulus to the gender imbalance that we have in physical oceanography."

Wåhlin said last summer that she was the only woman on an AUV conference. She has struggled to build the networks in her area that she believes are suitable for men, and now says she never refuses a request for mentoring from a student.

something; It's because I think it's good for science. In the past, we only used a maximum of 50% of the pool of good scientists, and I want to make sure we use 100% in the future. That's good for science, "Wåhlin said.

Wåhlin, who undertook her first expedition to the West Antarctic Ice Sheet more than a decade ago, says she is driven by a long-standing desire to know the world around her.

"I wonder, I'm really wondering, what's up?" Said Wåhlin. "It's curiosity, no fear or anything else." Even as a little girl, she was delighted with the crabs she saw underwater when her parents sailed her and her two sisters off the Swedish west coast.

Sitting near the beach and suddenly looking at what's below the surface of the water is very, very fascinating, "Wåhlin said. "And I never let go of this fascination."

In a sense, Ran is an extension of it. Throughout the Antarctic voyage, the racing joke aboard the Palmer was that Ran Wåhlin's obstinate child was always late, hard to communicate, and doing the unexpected.

After the submarine has wrestled against the Hugin with a small Zodiac, the submarine is hoisted to a tied winch rope and back on deck of Nathaniel B. Palmer.

Carolyn Beeler / The World

The AUV is equipped with 19 sensors that measure sea temperature, salinity and speed to determine how much warm water Thwaites has reached and how much meltwater is leaking out.

Sonars that point both up and down give scientists and geophysicists on the ship a very detailed view of the bottom of the ice shelf and the top of the seafloor.

The expedition this winter was the first Antarctic test mission for Wåhlin and her submarine. The goal was to master the deployment and salvage of the AUV under ever-changing Antarctic conditions.

"It's a high-tech instrument, but it's one of the hurdles that Wåhlin and her five-strong team encountered underscore the difficulty of doing something in the Antarctic.

Big waves made it a challenge Defeat the two-ton submarine with small inflatable Zodiac boats to bring it back to Palmer. Likewise, raising the submarine on deck – with a winch wire and a metal A-frame – was strong against the wind and waves that rocked the ship.

The submarine did not dive in early missions, so Wåhlin had to adjust his buoyancy.

And because sea ice can form overnight in the Amundsen Sea, Wåhlin has programmed the submarine to stay away from newly formed ice and wait for new instructions, where it reappears to avoid damage. About three weeks into the trip, Ran had to miss an important test mission, so the goal of sending the submarine under the ice was to be postponed to the next expedition in two years. Instead, Wåhlin concentrated on examining the warm water circulating in front of the glacier. He graduated on 1 February 2019 his first test mission of the expedition in the Strait of Magellan.

Carolyn Beeler / The World [19659028] A & # 39; small tour among the Thwaites & # 39;

After a month at sea and several test missions, Wåhlin was given the opportunity to send Ran on a mission off the gently sloping surface of the Thwaite Ice Shelf.

She programmed The submarine follows two deep valleys, ditches at exactly the right depth to direct the middle-pillar layer of warm water that melts the ice shelf to the face of the glacier.

"The valleys are the places where warm water meets the water. We believe there is a current here with warm water flowing under the Thwaites," Wåhlin said. "She measures it while we speak."

After 13 hours in the water, Wåhlin spotted an orange flash in the distance. Ran was back.

"We actually did a little tour of Thwaites," Wåhlin revealed with a mischievous grin from her place at the windows at the front of the ship's bridge. "We did not want to tell anyone before, but we did it now."

"Historically," she said, smiling broadly. "I just wish everyone would feel that feeling once in a lifetime."

Wåhlin hurried to the quarterdeck, where the rest of her team Ran threw off the salt water and downloaded the historical data she had just collected. The words "Good Luck," someone scribbled in the mud on the surface of the submarine, were still intact.

The remains of the words "Good Luck" survived Ran's first mission under the Thwaites Ice Shelf.

Carolyn Beeler / The World

Aleksandra Mazur of Wåhlin, who was thrilled that her mentor added another name to her name.

"She was the first woman to send [an AUV] under a ice shelf!" Mazur later said.

Mazur, a colleague of Gothenburg University and a former student of Wåhlin, had worked on Rans first test runs in Swedish fjords last summer. On the day Ran finally fell under Thwaites, Mazur said she felt like a polar explorer.

"It is not often to be in a place where nobody has been before and to do things that no one has done before, after all these years you sacrifice for study and research, and it is one I'm just so happy. "

Scientists gathered in the ship's lab to look at early pictures of the Hugin from the seabed at Thwaites.

Carolyn Beeler / Die Welt

The goal is to eliminate uncertainty. [1965] 19659028] The next day, half of the scientists on this ship crowded in front of a computer to gaze at the high-resolution images of the seabed Ran had taken – they could contain clues to the glacier's past and future.

"Es is like me I've been blind all my life, and now I've put on glasses and can see every single leaf on the tree, "said the University of Alabama, Becky Minzoni, a sedimentologist about the black-and-white images that showed traces of how tank marks on the seabed.

They revealed much finer details than the ship's sonar, with which Minzoni and the geophysicists of the ship had mapped the seabed and identified the best locations for taking sediment samples. "It's beautiful," said Minzoni.

"It's as if I've been blind all my life and now put on glasses and can see every single leaf on the tree."

Becky Minzoni, University of Alabama

Wåhlin was satisfied with Ran's measurements of temperature, salinity, oxygen, and water velocity, as well as the water samples she had collected under the ice shelf.

"Nobody has ever seen such data before," Wåhlin said.

For the first time, scientists at the Palmer found and measured the warm water that they thought would melt the fast flowing central part of Thwaites.

Wåhlin can estimate under the ice shelf how much warm water the ice has reached and trace exactly where it came from.

These data will eventually help improve sea-level models, the ultimate goal of the five-year international Thwaites research collaboration.

"I think the big take away here is not a new alarm or that we all need to panic. It's just that we have more data so we can have more reliable estimates for the future, "Wåhlin said.

Currently, the United Nations Intergovernmental Panel on Climate Change estimates that sea levels could rise anywhere between 8 inches and 2.7 feet by 2100. A huge range and the entire gap in uncertainty could only be filled by Thwaites.

For Wåhlin, eliminating this insecurity is the ultimate goal.

"We only have one planet on which to live," Wåhlin said. "I think it's fair to say that we should understand what's going on and what's going on and what we can expect in the future."

This story was co-published with PRIs The World, the award-winning public radio, show and podcast on global topics, news and insights from BBC, WGBH, PRI and PRX.


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