Sleek robots the size of dolphins are providing a better understanding of how and why the ice sheets off the coast of West Antarctica are melting so rapidly, according to researchers at the California Institute of Technology. Their findings were published online in the Nov. 10 issue of the journal Nature Geoscience.
As a result of the study, researchers now know that swirling ocean eddies play a large role in transporting warm water to West Antarctica. This new information will give scientists a better measure of how quickly the ice is melting and, consequently, how fast sea levels will rise.
“When you have a melting slab of ice, it can either melt from above because the atmosphere is getting warmer or it can melt from below because the ocean is warm,” explained lead author Andrew Thompson in a report by Reuters. “All of our evidence points to ocean warming as the most important factor affecting these ice shelves, so we wanted to understand the physics of how the heat gets here.”
Because ships face difficulties in West Antarctic waters, the researchers had to come up with a different way of testing the sea water. For a solution, they turned to sleek, six-foot-long, dolphin-sized robots.
The gliding robots’ small size helps make them extremely energy efficient and they can take ocean samples for a longer period of time than large ships. The ‘dolphins’ also glide to the surface every few hours to communicate with the researchers by means of a cell phone-like device, providing them with a continuous stream of data.
Thompson and his colleagues dropped their sea-faring robots into the waters of the Weddell Sea off the coast of Antarctica in January 2012, where they spent the next two months moving up and down the water column, according to a university statement. The robotic vehicles dove as deep as a kilometer below the water’s surface.
This up and down process is crucial for studying ocean stratification as well as how water density changes with depth, Thompson said. As a result, the robots may be giving scientists the most detailed picture yet of activity deep beneath the Southern Ocean.
After analyzing the data, the researchers found that a warm layer of water was being transported to the Antarctic region from warmer latitudes by swirling eddies, which behave similarly to atmospheric storms.
“It’s sort of like the weather,” said Thompson. “You know it’s going to be warm in the summer and cold in the winter, but on a day to day basis it could be cold in the summer just before a storm came in.”
“Eddies to the same thing in the ocean, so unless you understand how the temperature of currents is changing from day to day—information we can actually collect with the gliders—then you can’t understand what the long-term heat transport is,” he explained.
Thompson says he hopes future missions will look at the transfer of carbon dioxide between the ocean and the air.