Robot Ocean Gliders Study How Antarctica's Polar Ice Melts from Below

As temperatures climb and the climate changes, the ice sheets on the coast of West Antarctica continue to melt. Now, scientists are using some new tools to study melting polar ice. Robotic ocean gliders are revealing a bit more about how and why this melt is occurring.

"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," said Andrew Thompson, the lead author of the new study, in a news release. "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 there."

Usually, scientists use ships to lower instruments through the water to collect ocean temperature data. Yet these techniques can be problematic since it's difficult to reach some areas with ships. That's why, in this case, the researchers employed ocean gliders.

The gliders are small, only about six feet long, and are energy efficient. They can sample the ocean for much longer periods than large ships can. When the gliders surface every few hours, they "call" the scientists with a mobile phone-like device to deliver information that it's collected.

Using the gliders, the scientists found that swirling ocean eddies, similar to atmospheric storms, play an important role in transporting warm waters to the Antarctic coast.

"Eddies are instabilities that are caused by ocean currents, and we often compare their effect on the ocean to putting a spoon in your coffee," said Thompson. "If you pour milk in your coffee and then you stir it with a spoon, the spoon enhances your ability to mix the milk into the coffee and that is what these eddies do. They are very good at mixing heat and other properties."

The findings have implications for better understanding how this warming will affect melting ice and, in turn, rising ocean levels. Using these robots, the scientists can further their studies in order to better understand the impacts of climate change.

The findings are published in the journal Nature Geoscience.