The impact of a collapsed glacier on an underwater landscape: How the International Thwaites Glacier could be a natural dam
There is significant glacier loss and every effort is being made to reduce it. A small reduction in temperature change can make a big difference.
The past few years, however, have seen “a revolution in using satellite images to monitor glacier changes,” Rounce said, allowing scientists to come up with estimations for each individual glacier.
A group of US and British scientists traveled to the International Thwaites Glacier in late last year to learn more about the changes of the remote coastline.
The scientists were surprised at a second finding. They found an underwater landscape that was more complex than they expected, dominated by terraces and crevasses which went all the way through the ice shelf.
The complete collapse of the Thwaites itself could lead to sea level rise of more than two feet (70 centimeters), which would be enough to devastate coastal communities around the world. But the Thwaites is also acting like a natural dam to the surrounding ice in West Antarctica, and scientists have estimated global sea level could ultimately rise around 10 feet if the Thwaites collapsed.
While it could take hundreds or thousands of years, the ice shelf could disintegrate much sooner, triggering a retreat of the glacier which is both unstable and potentially irreversible.
Monitoring glacier melt rate in Thwaites by robot swaming through an ice hole: A probe for glacier melting and the seabed
They used a hot water drill to bore a hole into the ice and then sent instruments down to measure the amount of water in the glacier over a five day period.
The camera shows not just the melting water, but the crevasses and the seabed when a skinny robot wended its way through the hole in the ice. The sea anemones were swimming under the ice.
According to an associate professor at Cornell University, it was possible to take data from the sea floor to the ice.
Peter Davis, an oceanographer at the BritishAntarctic Survey, told CNN that the results of the research reveal a very nuanced and complex picture.
Melting is being suppressed by a layer of colder, fresher water at the base of the glacier, between the ice shelf and the ocean, according to the research.
Davis said in a statement that despite small amounts of melting there is still rapid glacier retreat, which makes it difficult to push the glacier out of balance.
The areas under the ice that were the highest in melt rate were the ones where there were cracks and steep features. These divert the cold, protective melt water, allowing the heat to reach the ice, and melt it to widen crevasses.
The glaciers were changing, we knew that. We knew it was related to ocean temperature. We knew there was melting going on. We knew the atmosphere was warm. And we knew that the glaciers were falling apart,” Schmidt said.
The research can help make more accurate projections of sea level rise, which will be fed into efforts to mitigate climate change and protect coastal communities. He also hopes that it causes people to sit and take notice of the changes that are happening.
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, there’s just material streaming out of the glacier,” said robot creator and polar scientist Britney Schmidt of Cornell University.
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.
Warm ocean water melting the underside of the ice is believed to be the cause of grounding-line retreat. Climate change has moved wind patterns, which has allowed warm water to flow toward the West Antarctic.
Richard Alley of Pennsylvania State University, who wasn’t part of the studies, stated that the new work will give us an important look at processes affecting the crevasses that may eventually break and cause loss of ice shelf.
The work comes out of a massive $50 million multi-year international research effort to better understand the widest glacier in the world. The Florida-sized glacier has become known as the “Doomsday Glacier” because of its size and how much water it could accumulate if it all melted.
“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 key to seeing how bad the conditions are is going to the main trunk and seeing the melting from beneath. The helicopter landing on ice, instead of a heavier airplane, would be difficult and it could take years to figure it out, according to Eric Rignot, the co-author of the studies.
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.
The discovery of the anemones in front of the ice-ocean interface — a touching experience for a giant exoplanet
Ted Scambos of the National Snow and Ice Data Center, who wasn’t part of the studies, said the results add to understanding how Thwaites is diminishing.
This is still going to be a major issue in a century. “But our better understanding gives us some time to take action to slow the pace of sea level rise.”
“To accidentally discover them in this environment was very cool, and I can safely say it was,” he said. “We were so tired that you kind of wonder like, ‘am I really seeing what I’m seeing?’ You know because there are these little creepy alien guys (the anemones) hanging out on the ice-ocean interface.
There are these sparkling stars in the background that were picked up from the glacier. And then the anemones. It’s sort of a crazy experience.