Stronger Winds Behind Mysterious Growth in Antarctic Sea Ice, Study Suggests

Strong westerly winds may be the reason Antarctic sea ice continues to expand in spite of a warming climate, a new study shows.

Even as Arctic sea ice is hitting record lows, the Antarctic has been reaching record highs, baffling researchers and fueling arguments posed by global warming skeptics.

"The overwhelming evidence is that the Southern Ocean is warming," Jinlun Zhang, an oceanographer at the University of Washington's Applied Physics Laboratory, said in a statement. "Why would sea ice be increasing? Although the rate of increase is small, it is a puzzle to scientists."

In an effort to solve this mystery, Zhang turned to a computer simulation including detailed interactions between wind and sea. The results, published in the Journal of Climate, point to stronger polar winds as the reason the Antarctic contains more sea ice today than the 1970s.

The polar vortex located around the South Pole is not only stronger than it was 40 years ago, but also has more convergence. Both result in the ice being shoved together, causing it to become thicker. Furthermore, surrounding water and thin ice are exposed to freezing winds, accelerating ice growth in these areas.

In all, the study showed that thick ice, as defined as more than 6 feet deep, increased by roughly 1 percent per year between 1979 to 2010. The amount of thin ice, meanwhile, remained relatively constant.

"You've got more thick ice, more ridged ice, and at the same time you will get more ice extent because the ice just survives longer," Zhang said.

The increase in Antarctic ice is small in comparison to the amount lost in the Arctic, leading to an overall decrease worldwide, Zhang notes.

What's more, should global warming continue at current rates, warmer temperatures will eventually outweigh the effects of the wind, the researcher said.

"If the warming continues, at some point the trend will reverse."