Submarine reveals true state of Antarctic sea ice

By Karl Gruber 24 November 2014
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Data from an underwater robot shows that Antarctic sea ice is thicker and more deformed than thought

A THOROUGH STUDY of the dark side of Antarctic sea ice has revealed the ice is thicker and more deformed than previously thought.

An autonomous underwater vehicle (AUV) sent to explore Antarctic waters on the coastal regions of the Weddell Sea, the Bellingshausen Sea and off Wilkes Land in eastern Antarctica, has returned data showing sea-ice up to 16m thick and that three-quarters of it is deformed.

“Much in the same way a new microscope (or telescope) lets us see so much more, and then understand so much more…the 3D maps produced by the AUV provides a completely new view of sea ice structure and will inevitably lead to far greater understanding of the processes driving it,” says Dr. Guy Williams, an oceanographer from the University of Tasmania, who co-led the study appearing this week in the journal Nature Geosciences.

Underwater robot in Antarctica better than ships

Previous attempts to measure Antarctic sea ice employed limited drilling and visual inspections from ships. These approaches suggested that Antarctic waters where covered by a relatively thin layer of ice.

The findings confirm long-held suspicions that current measurements of Antarctic ice thickness were biased, says Guy. “Measuring is believing”, he says. “While I think it is fair to say that the community has long thought its previous ship-based or manual drill-line estimates are biased to thin-ice, this result proves it.”

Antarctic sea ice study important for climate change

The new findings are likely to open a new line of research and understanding about the anatomy of Antarctic ice says Dr. Stephen Ackley, a sea ice geophysicist from the University of Texas at San Antonio, in the USA.

This will be particularly important for near-coastal regions, says Stephen, as sea-ice formation is the driver for ‘Antarctic Bottom Water’, the main component of the deep ocean all around the world.

This technology, coupled with Lidar surface surveying over these mapped areas, presents the best combination of technologies needed to determine sea ice thickness, he says.

Such measurements will become important for future efforts to better understand how climate change will impact the ocean environment, says Stephen. Models of air-ice-ocean interaction “will be critical in correctly forecasting the effects of future global warming on the Southern Ocean environment”, he says.

Now the team responsible for the AUV development is working on the next generation of such vehicles, says Guy.

“The WHOI (Woods Hole Oceanographic Institution) team responsible for the AUV we used is now developing a smaller, lighter AUV to cover a greater area of sea ice away from the ship,” he says. “And as an exciting bonus, we are now developing unmanned aerial platforms that will work in concert with the AUVs to provide vital information from above and below the sea ice, at the same time.”