Sea ice levels are expected to reach an all time high this year, and roaring winds could be the cause.
A recent climate model found stronger polar winds led to more sea ice, even on a warming Earth, a University of Washington press release reported.
"The overwhelming evidence is that the Southern Ocean is warming," author Jinlun Zhang, an oceanographer at the UW Applied Physics Laboratory, said. "Why would sea ice be increasing? Although the rate of increase is small, it is a puzzle to scientists."
Zhang determined wind from the South Pole could be responsible for about 80 percent of the dramatic rise in sea ice volume.
"The polar vortex that swirls around the South Pole is not just stronger than it was when satellite records began in the 1970s, it has more convergence, meaning it shoves the sea ice together to cause ridging. Stronger winds also drive ice faster, which leads to still more deformation and ridging. This creates thicker, longer-lasting ice, while exposing surrounding water and thin ice to the blistering cold winds that cause more ice growth," the press release reported.
A computer simulation showed the volume of thick sea ice increased by about one inch per year between 1979 and 2010, but thinner ice showed little change. When the model left the polar wind at a constant level, the sea ice increased by only 20 percent as much.
A previous study by the same researcher concluded changes in water density could explain the remaining percentage of sea-ice increase.
"People have been talking about the possible link between winds and Antarctic sea ice expansion before, but I think this is the first study that confirms this link through a model experiment," Axel Schweiger, a polar scientist at the UW Applied Physics Lab, said. "This is another process by which dynamic changes in the atmosphere can make changes in sea ice that are not necessarily expected."
Researchers are unsure what has been causing the winds to get stronger, but suspect that global warming is to blame.
Zhang warned that if the planet continues to warm it will counteract the contradiction.
"If the warming continues, at some point the trend will reverse," Zhang said.
