The problem of Thwaites, Greenland, and the Antarctic: How much does it take to melt an ice sheet? A Cornell University Earth scientist’s perspective
The Intergovernmental Panel on Climate Change predicts that sea levels will probably rise by between 38 and 77 centimetres by 2100, but the collapse or melting of ice sheets in Greenland and the Antarctic could theoretically contribute an additional metre. Britney Schmidt is an Earth scientist at Cornell University in Ithaca, New York and is a co-author of both papers.
Rounce said the past few years had seen a revolution in using satellite images to monitor glacier changes.
In a pair of papers published today in the journal Nature, scientists describe what Icefin and other instruments have discovered underneath all that ice. Simply put: trouble. Models of future sea-level rise characterize the bit of Thwaites that’s floating on the ocean—known as an ice shelf—as having a fairly simple, flat underside, but the robot found that 10 percent of it is way more complex. The melting of the walls in the terraces is happening much faster than in the flat areas. That small portion contributes 25 percent of the melting that we see, according to a Earth and planetary scientist at Cornell University. She is the lead author of one of the papers. “So it’s a really outsized impact.”
The scientists found even though the glacier is receding, the rate of melting beneath much of the flat part of the ice shelf was lower than expected. The melt rate was less than anticipated according to the study.
The collapse of Thwaites could cause sea level rise of more than two feet, which would be a huge concern for 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.
Discovery of sea anemones swimming in a glacier that is melting at the seafloor-ocean interface: the case of Thwaites
Using a hot water drill, they bored a hole nearly 2,000 feet (600 meters) deep into the ice and, over a five-day period, sent down various instruments to take measurements from the glacier.
The skinny robot entered the hole in the ice using a jet of hot water, and the cameras saw more than just the melting water, the crevasses and the seabed. It showed sea anemones swimming in the ice.
A Cornell University professor who is a lead author on one of the papers tells CNN that it was able to collect data from the sea floor all the way to the ice.
The results of the research reveal “a very nuanced and complex picture,” Peter Davis, an oceanographer at the British Antarctic Survey and a lead author on the other paper, told CNN.
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 that the glacier is still in trouble because it doesn’t take a lot to push it out of balance.
The research team was able to show that the area was experiencing rapid melting. Warm, salty water was able to funnel through and widen cracks and crevasses, contributing to instabilities in the glacier.
“We knew these glaciers were changing. The ocean temperature is related to it. We were well aware that there was going to be melting. We knew that the atmosphere was warming. And we knew that the glaciers were falling apart,” Schmidt said.
Davis said the research can help make more accurate projections about sea level rise, which can be fed into efforts to mitigate climate change and protect coastal communities. He hopes it will make people sit up and take notice of what is happening.
The scientists used a robot that was 13 feet long to swim under the ground where ice first juts over the sea and saw a shimmery critical point in Thwaites’ chaotic break up.
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.”
Researchers think the retreat is the result of warm ocean water melting the ice. Climate change has shifted wind patterns in the region, allowing a patch of warm water to flow towards the West Antarctic.
Both papers might help to clarify what’s missing from simple models of Antarctic ice that don’t seem to capture large changes thought to have happened during warmer periods of Earth’s history, says Eric Steig, a glaciologist at the University of Washington in Seattle. The results show that the ice might be more sensitive thanks to the fact that it can retreat rapidly even though it has low rates of melting from underneath. “Maybe you don’t need as much melt to affect the structural integrity,” Steig says.
The $5 million international research effort was done to better understand the widest glacier in the world. The Florida-sized glacier has gotten the nickname the “Doomsday Glacier” because of how much ice it has and how much seas could rise if it all melts — more than 2 feet (65 centimeters), though that’s expected take hundreds of years.
“Thauites is much more quickly changing than when we began this work five years ago, and even more so since we have been in the field three years ago,” said Oklahoma State University ice researcher, who isn’t part of either study. The change is expected to continue over the next few years.
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 studies co-author 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.
The anemones: what happened to Scambos when he was a glacier at the National Snow and Ice Data Center
Ted Scambos is a researcher with the National Snow and Ice Data Center who wasn’t part of the studies.
“Unfortunately, this is still going to be a big issue a century from now,” he said. “But our better understanding gives us some time to take action to slow the pace of sea level rise.”
“To find them here in this environment was cool, and to accidentally do it was fantastic,” he said in an interview. We were so tired you wondered if I really saw what I was seeing. You know because there are these little creepy alien guys (the anemones) hanging out on the ice-ocean interface.
“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. “Then the anemones.” It’s really quite a wild way to experience it.