FEBRUARY 15, 2023
Scientists got their first close-up look at what is eating away part of Antarctica's Thwaites ice shelf, nicknamed the "doomsday glacier" because of how much ice it has and how much seas could rise if it all melts — and it's both good and bad news.
Using a 13-foot pencil-shaped 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'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 the Thwaites Glacier. But with the robot (named Icefin) lowered down a slender, 1,925-foot 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, the lead author of one of two studies published Wednesday in the journal Nature.
A robot nicknamed Icefin operates under the sea ice near McMurdo Station in Antarctica in 2020.
SCHMIDT/LAWRENCE/ICEFIN/NASA PSTAR RISE UP VIA AP
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 massive $50 million multiyear international research effort to better understand the Florida-sized glacier, which could make sea levels rise more than 2 feet if it melts, though that's expected to take hundreds of years.
At about 80 miles in width, the Thwaites Glacier is the widest on Earth. As the planet continues to warm, ice that composes the glacier is melting, like much of the sea ice that surrounds the Earth's north and south poles. The glacier's rapid changes have concerned scientists for years.
Researchers say the glacier is in a phase characterized by "rapid retreat," or "collapse," when a broader geological timeline is considered. A study conducted by marine physicist Alastair Graham at the University of South Florida last year suggested that, despite observations indicating the glacier's melting rate had slowed down compared with previous evaluation periods, it would likely accelerate soon.
"Similar rapid retreat pulses are likely to occur in the near future," the study said.
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 involved in either study. "I am definitely expecting the rapid change to continue and accelerate over the next few years."
Pennsylvania State University glaciologist Richard Alley, who also wasn't part of the studies, said the new work "gives us an important look at processes affecting the crevasses that might eventually break and cause loss of much of the ice shelf."
Now for the good news: Much of the flat underwater area the scientists explored is melting much slower than they expected.
But that doesn't really change how much ice is coming off the land part of the glacier and driving up sea levels, Davis said.
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 massive $50 million multiyear international research effort to better understand the Florida-sized glacier, which could make sea levels rise more than 2 feet if it melts, though that's expected to take hundreds of years.
At about 80 miles in width, the Thwaites Glacier is the widest on Earth. As the planet continues to warm, ice that composes the glacier is melting, like much of the sea ice that surrounds the Earth's north and south poles. The glacier's rapid changes have concerned scientists for years.
Researchers say the glacier is in a phase characterized by "rapid retreat," or "collapse," when a broader geological timeline is considered. A study conducted by marine physicist Alastair Graham at the University of South Florida last year suggested that, despite observations indicating the glacier's melting rate had slowed down compared with previous evaluation periods, it would likely accelerate soon.
"Similar rapid retreat pulses are likely to occur in the near future," the study said.
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 involved in either study. "I am definitely expecting the rapid change to continue and accelerate over the next few years."
Pennsylvania State University glaciologist Richard Alley, who also wasn't part of the studies, said the new work "gives us an important look at processes affecting the crevasses that might eventually break and cause loss of much of the ice shelf."
Now for the good news: Much of the flat underwater area the scientists explored is melting much slower than they expected.
But that doesn't really change how much ice is coming off the land part of the glacier and driving up sea levels, Davis said.
A robot nicknamed Icefin is deployed at Thwaites glacier in Antarctica in January 2020. The pencil-shaped robot is giving scientists their first look at the forces eating away at the Thwaites glacier.
DICHEK/ICEFIN/ITGC VIA AP
Davis said the melting isn't nearly the problem. 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.
And more bad news: the new research is from the eastern, larger and more stable part of Thwaites. Researchers couldn't safely land a plane and drill a hole in the ice in the main trunk, which is breaking up much faster.
The key to seeing exactly how bad conditions are on the glacier would require going to the main trunk and looking at the melting from below. But that would require a helicopter to land on the ice instead of a heavier airplane and would be incredibly difficult, said Eric Rignot of the University of California Irvine.
The main trunk's glacier surface "is so messed up by crevasses, it looks like a set of sugar cubes almost. There's no place to land a plane," NSF's Cutler said.
Ted Scambos of the National Snow and Ice Data Center said the recent results add to understanding how Thwaites is diminishing.
"Unfortunately, this is still going to be a major issue a century from now," Scambos said in an email. "But our better understanding gives us some time to take action to slow the pace of sea level rise."
When the skinny robot wended its way through the hole in the ice – made by a jet of hot water – the cameras showed not just the melting water, the crucial crevasses and seabed. It also showed critters, especially sea anemones, swimming under the ice.
"To accidentally find them here in this environment was really, really cool," Schmidt said in an interview. "We were so tired that you kind of wonder like, 'am I really seeing what I'm seeing?'"
"In the background is like all these sparkling stars that are like rocks and sediment and things that were picked up from the glacier," Schmidt said. "And then the anemones. It's really kind of a wild experience."
Davis said the melting isn't nearly the problem. 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.
And more bad news: the new research is from the eastern, larger and more stable part of Thwaites. Researchers couldn't safely land a plane and drill a hole in the ice in the main trunk, which is breaking up much faster.
The key to seeing exactly how bad conditions are on the glacier would require going to the main trunk and looking at the melting from below. But that would require a helicopter to land on the ice instead of a heavier airplane and would be incredibly difficult, said Eric Rignot of the University of California Irvine.
The main trunk's glacier surface "is so messed up by crevasses, it looks like a set of sugar cubes almost. There's no place to land a plane," NSF's Cutler said.
Ted Scambos of the National Snow and Ice Data Center said the recent results add to understanding how Thwaites is diminishing.
"Unfortunately, this is still going to be a major issue a century from now," Scambos said in an email. "But our better understanding gives us some time to take action to slow the pace of sea level rise."
When the skinny robot wended its way through the hole in the ice – made by a jet of hot water – the cameras showed not just the melting water, the crucial crevasses and seabed. It also showed critters, especially sea anemones, swimming under the ice.
"To accidentally find them here in this environment was really, really cool," Schmidt said in an interview. "We were so tired that you kind of wonder like, 'am I really seeing what I'm seeing?'"
"In the background is like all these sparkling stars that are like rocks and sediment and things that were picked up from the glacier," Schmidt said. "And then the anemones. It's really kind of a wild experience."
On thin ice: Melting of the doomsday glacier in Antarctica could raise sea levels by 65 centimetres
But scientists warn that Thwaites Glacier, which is slowly melting, would be a proverbial drop in the bucket when it comes to potential sea level rise from Antarctica.
Thwaites Glacier in 2012. Credit: NASA ICE / James Yungel, CC BY 2.0 via Wikimedia Commons.
Modelling shows that the thawing of just one of Antarctica’s glaciers, the Thwaites Glacier in the West Antarctic Ice Sheet, could raise global sea levels by an average of more than half a metre.
As the global climate warms, ice in the polar regions melts, causing sea levels to rise and making the salty ocean waters fresher.
It’s not that complicated.
But scientists are still poring over data to try and underscore the urgency of the potentially catastrophic impact of human-induced climate change on the global ecosystem and on civilisation itself.
Researchers from the British Antarctic Survey revealed their findings on the vulnerability of the Thwaites Glacier to collapse in two papers published (here and here) in Nature. The results come from measurements taken by drilling through approximately 587 metres of ice and using semi-autonomous underwater vehicles to measure oceanic properties around the glacier.
Their projections show that complete collapse of the Thwaites Glacier could increase global sea levels by 65 cm over a century or so.. The glacier’s collapse could also destabilise neighbouring glaciers, leading to an additional three-metre rise.
Senior scientist with the Australian Antarctic Division, Dr Ben Galton-Fenzi, is a glaciologist who spoke with Cosmos about the researchers’ findings.
Galton-Fenzi, who is not part of the team that published either Nature article, notes that the Thwaites Glacier has been dubbed the “Doomsday Glacier” and has been rapidly retreating for years.
“The biggest reason why folk think it started to retreat is really due to changes in the ocean,” Galton-Fenzi explains. “Due to climate change driving a shift in the winds in Antarctica, which turns more warm water onto the shelf, you get that relatively warmer water driving the increase in melting. Then you’re actually exposing more ice to the ocean, so it then melts more.”
The glaciologist notes that much of the modelling has a relatively high uncertainty because so much ice is below sea level, but recent technological developments like autonomous vehicles has increased scientists’ ability to see below the surface.
Galton-Fenzi says sea level rise is already happening.
“The bottom line for me is that it’s already changing. Sea levels are going to go up, and the oceans are going to get fresher. If the oceans get fresher, that’s going to change things like the global overturning circulation, the ocean conveyor belt. The question is: given the amount of warming is already in the atmosphere and in the oceans, how much sea level rise are we already committed to now?
“The biggest uncertainty in future sea level comes from Antarctica. It’s massive. The projections are several tens of centimetres by the end of the century, but it could be metres. A lot of that isn’t going to come from the West Antarctic Ice Sheet, it’s going to come out of the East Antarctic Ice Sheet in our backyard,” Galton-Fenzi adds.
The Nature papers come as other research published in Nature Communications notes that if global warming is not restricted to 1.8°C, then melting from the Antarctic and Greenland ice sheets alone will see sea levels rise around 1.4 metres.
\
“There are a lot of communities that live within what we call the low elevation coastal zone,” says University of New South Wales social sciences PhD candidate Anne Maree Kreller. “We’re talking about a meter – a lot of people live in just a meter above sea level. There are estimates that approximately 85% of the Australian population live on the coast.”
Kreller specialises in social movements and community-based decision-making.
“Start thinking about sea level rise, and you start thinking about the tides, storm surges, and you’ve got this accumulation of risks to human communities. Think about the global community, like Tuvalu and Bangladesh where people live in the Delta. What happens when you start to have storms and cyclones is really catastrophic. And the thing about sea level rise that makes it really difficult to connect to people’s daily life, is its slow moving.”
Kreller says there are two aspects to tackling sea level rises.
“One is mitigation, and stopping the use of fossil fuels and addressing this, and the other is the obviously the adaptation space and starting to ask some of those questions that are quite difficult,” Kreller explains.
But scientists warn that Thwaites Glacier, which is slowly melting, would be a proverbial drop in the bucket when it comes to potential sea level rise from Antarctica.
Thwaites Glacier in 2012. Credit: NASA ICE / James Yungel, CC BY 2.0 via Wikimedia Commons.
Modelling shows that the thawing of just one of Antarctica’s glaciers, the Thwaites Glacier in the West Antarctic Ice Sheet, could raise global sea levels by an average of more than half a metre.
As the global climate warms, ice in the polar regions melts, causing sea levels to rise and making the salty ocean waters fresher.
It’s not that complicated.
But scientists are still poring over data to try and underscore the urgency of the potentially catastrophic impact of human-induced climate change on the global ecosystem and on civilisation itself.
Researchers from the British Antarctic Survey revealed their findings on the vulnerability of the Thwaites Glacier to collapse in two papers published (here and here) in Nature. The results come from measurements taken by drilling through approximately 587 metres of ice and using semi-autonomous underwater vehicles to measure oceanic properties around the glacier.
Their projections show that complete collapse of the Thwaites Glacier could increase global sea levels by 65 cm over a century or so.. The glacier’s collapse could also destabilise neighbouring glaciers, leading to an additional three-metre rise.
Senior scientist with the Australian Antarctic Division, Dr Ben Galton-Fenzi, is a glaciologist who spoke with Cosmos about the researchers’ findings.
Galton-Fenzi, who is not part of the team that published either Nature article, notes that the Thwaites Glacier has been dubbed the “Doomsday Glacier” and has been rapidly retreating for years.
“The biggest reason why folk think it started to retreat is really due to changes in the ocean,” Galton-Fenzi explains. “Due to climate change driving a shift in the winds in Antarctica, which turns more warm water onto the shelf, you get that relatively warmer water driving the increase in melting. Then you’re actually exposing more ice to the ocean, so it then melts more.”
The glaciologist notes that much of the modelling has a relatively high uncertainty because so much ice is below sea level, but recent technological developments like autonomous vehicles has increased scientists’ ability to see below the surface.
Galton-Fenzi says sea level rise is already happening.
“The bottom line for me is that it’s already changing. Sea levels are going to go up, and the oceans are going to get fresher. If the oceans get fresher, that’s going to change things like the global overturning circulation, the ocean conveyor belt. The question is: given the amount of warming is already in the atmosphere and in the oceans, how much sea level rise are we already committed to now?
“The biggest uncertainty in future sea level comes from Antarctica. It’s massive. The projections are several tens of centimetres by the end of the century, but it could be metres. A lot of that isn’t going to come from the West Antarctic Ice Sheet, it’s going to come out of the East Antarctic Ice Sheet in our backyard,” Galton-Fenzi adds.
The Nature papers come as other research published in Nature Communications notes that if global warming is not restricted to 1.8°C, then melting from the Antarctic and Greenland ice sheets alone will see sea levels rise around 1.4 metres.
\Sea level rise contributions from the Antarctic and Greenland ice sheets, and maps projected 2150 CE Antarctic ice sheet surface elevation following different greenhouse gas emission scenarios. Credit: Jun-Young Park.
Lead author Jun-Young Park tells Cosmos that “recent research says that 1m sea level rise in 2100 CE can threaten more than 400 million people.”
Lead author Jun-Young Park tells Cosmos that “recent research says that 1m sea level rise in 2100 CE can threaten more than 400 million people.”
“There are a lot of communities that live within what we call the low elevation coastal zone,” says University of New South Wales social sciences PhD candidate Anne Maree Kreller. “We’re talking about a meter – a lot of people live in just a meter above sea level. There are estimates that approximately 85% of the Australian population live on the coast.”
Kreller specialises in social movements and community-based decision-making.
“Start thinking about sea level rise, and you start thinking about the tides, storm surges, and you’ve got this accumulation of risks to human communities. Think about the global community, like Tuvalu and Bangladesh where people live in the Delta. What happens when you start to have storms and cyclones is really catastrophic. And the thing about sea level rise that makes it really difficult to connect to people’s daily life, is its slow moving.”
Kreller says there are two aspects to tackling sea level rises.
“One is mitigation, and stopping the use of fossil fuels and addressing this, and the other is the obviously the adaptation space and starting to ask some of those questions that are quite difficult,” Kreller explains.
.jpg?quality=80&format=jpg&crop=0,0,2783,4947&resize=crop)
