Scientists have used an underwater vehicle to map the underside of Antarctica’s Dotson Ice Shelf, revealing unusual patterns that help understand rapid melting and rising sea levels. The study underscores the need for improved forecast models and continued research to understand future changes in ice shelf dynamics.

The first detailed maps of the underside of Antarctica’s floating ice shelf have revealed key clues about future sea level rise. An international team of researchers, including scientists from the University of East Anglia (UEA), has placed an unmanned underwater vehicle beneath the Dotson Ice Shelf in West Antarctica.

Underwater device “To run” Programmed to dive into the 350-metre-thick ice shelf and scan the ice above it with advanced sonar, the submarine travelled more than 1,000 kilometres back and forth under the shelf over 27 days, entering a 17-kilometre-wide gap.

Understanding ice shelf dynamics

An ice shelf is a mass of glacial ice fed from land by tidal glaciers floating above an ice shelf gap in the sea. The Dotson Ice Shelf is a part of the West Antarctic Ice Sheet, adjacent to the Thwaites Glacier, and is considered to have a potentially large impact on future sea level rise due to its size and location.

The researchers report their findings from this unique survey in a new paper published in the journal Nature. Science Developments.

They found some things that were expected, such as the glacier melting faster when strong undercurrents erode its base. Using a submersible, they were able to measure the currents beneath the glacier for the first time, proving why the western part of the Dotson Ice Shelf was melting so quickly. They also found evidence of very high melting along vertical faults running through the glacier.

But the team also saw new glacial patterns, raising questions. The mapping showed that the bottom wasn’t smooth, but a series of peaks and valleys of ice that formed into formations resembling plateaus and dunes. The researchers suggest that these may have been formed by water flowing under the influence of the Earth’s rotation.

High resolution mapping statistics

Lead author Anna Wolin, professor of oceanography at the University of Gothenburg in Sweden, said: “Previously, we used satellite data and ice cores to observe how the ice shelf changes over time. By taking the submarine into space, we were able to obtain high-resolution maps of the ice. It’s like seeing the far side of the moon for the first time.”

The expedition was conducted during a research expedition for the TARSAN project, a joint US-UK initiative under the Thwaites International Glacier Collaboration, in the drift ice regions of West Antarctica in 2022. The project is studying how atmospheric and oceanic processes affect the behavior of the Thwaites and Dotson ice shelves, neighboring ice shelves that behave differently.

Co-author Dr Rob Hall, from UEA’s School of Environmental Sciences, co-led the RV Nathaniel B Palmer expedition, which conducted observations from January to March 2022. He said: “Anna and her team successfully piloted the autonomous underwater vehicle “to run” More than 1,000 km beneath the Dotson Ice Shelf, a large amount of data and samples are being collected that will take several years to process and analyze.

“The incredible high-resolution images of the base of the ice shelf are the icing on the cake and will open up a whole new avenue for scientific investigation.”

The value of ice shelf melting

Professor Karen Heywood, also from UEA and one of the co-authors, is the UK lead scientist on the TARSAN project. She said: “It was a very exciting project to work on. When Anna sent us the first images of the base of the Dotson Ice Shelf we were very excited – no one had seen anything like it before. But we were also surprised – there were cracks and vortices appearing in the ice that we were not expecting. It was more like art!

“We wondered what could be the reason for this. All the glaciologists and oceanographers of the TARSAN project got together and brainstormed. It was like detective work, using basic ocean physics to test theories about the shape and size of the patterns under the ice. We were able to show for the first time some of the processes that melt the lower part of the ice shelf.

Professor Heywood added: “These ice shelves are already floating on the sea, so their melting does not directly affect sea level. However, melting ice shelves ultimately causes land-based glaciers to flow faster and become unstable, which leads to sea level rise, so these new observations will help the ice modelling community reduce the large uncertainty in future sea levels.”

Scientists now realize that there are many processes beneath the glaciers waiting to be discovered by future research missions.

“The mapping has given us new data that we need to look at more carefully. It is clear that many previous assumptions about the melting of the glacier base are not correct. Current models cannot explain the complex patterns we see. But this way we have a better chance of finding answers,” said Professor Wolin.

“Better models are needed to predict how fast ice shelves will melt in the future. It’s exciting to see oceanographers and glaciologists working together, combining remote sensing with oceanographic field data. This is essential to understanding the glacial changes that are happening; the ocean is the driving force.”

The group returns in January 2024 Morning We went to the Dotson Ice Shelf to repeat the survey, hoping to document the changes, but they had only completed one dive before. Morning disappeared under the ice.

“Although we had valuable data, we did not get everything we had hoped for,” said Professor Welin. “These scientific achievements were made possible thanks to the unique underwater vehicle it possesses. He ranThis research is essential to understanding the future of the Antarctic ice sheet and what we hope will be its replacement. Wound and let’s continue this important work.”