Antarctica’s ice paradox has yet another puzzling layer. Not only is the amount of sea ice increasing each year, but an underwater robot now shows the ice is also much thicker than was previously thought, a new study reports.
The Autonomous Underwater Vehicle (AUV), Jaguar, above, in the East Antarctic Sea, creating three-dimensional maps of the underside of sea ice. Photograph: WHOI
The discovery adds to the ongoing mystery of Antarctica’s expanding sea ice. According to climate models, the region’s sea ice should be shrinking each year because of global warming. Instead, satellite observations show the ice is expanding, and the continent’s sea ice has set new records for the past three winters. At the same time, Antarctica’s ice sheet (the glacial ice on land) is melting and retreating.
Measuring sea ice thickness is a crucial step in understanding what’s driving the growth of sea ice, said study co-author Ted Maksym, an oceanographer at the Woods Hole Oceanographic Institution in Massachusetts. Climate scientists need to know if the sea ice expansion also includes underwater thickening.
“If we don’t know how much ice is there is, we can’t validate the models we use to understand the global climate,” Maksym told Live Science. “It looks like there are significant areas of thick ice that are probably not accounted for.”
The findings were published today (Nov. 24) in the journal Nature Geoscience.
Like icebergs, much of Antarctica’s floating sea ice is underwater, hidden from satellites that track seasonal sea ice. And it’s difficult to take direct measurements from ships or drilling, because the thickest ice is also the hardest to reach, Maksym said.
The researchers were stuck aboard an icebreaker in 20-foot-thick (6 meters) pack ice for more than a week after taking advantage of a lead, or open water, that accessed thick ice, he said. “Obviously that carried some risk, and we were stuck until the wind changed direction again,” he said.