Stronger Winds May Increase Antarctica Sea Ice
Is sea ice melting or is it not? It seems that for every research paper supporting this evidence of global warming, there is another that is shows global warming is not happening. We tend to pay close attention to melting sea ice in the Arctic, however sea ice in Antarctica may be heading towards a record high this year. How? Polar winds.
A new study conducted by researchers at the University of Washington says that the reason there is more Antarctica sea ice than what was present in the 1970s may be due to stronger polar winds.
"The overwhelming evidence is that the Southern Ocean is warming," said author Jinlun Zhang, an oceanographer at the UW Applied Physics Laboratory. "Why would sea ice be increasing? Although the rate of increase is small, it is a puzzle to scientists."
His new study shows that stronger westerly winds swirling around the South Pole can explain 80 percent of the increase in Antarctic sea ice volume in the past three decades.
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.
In a computer simulation, thick ice — more than 6 feet deep — increased by about 1 percent per year from 1979 to 2010, while the amount of thin ice stayed fairly constant. The end result is a thicker, slightly larger ice pack that lasts longer into the summer.
"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.
"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," commented Axel Schweiger, a polar scientist at the UW Applied Physics Lab. "This is another process by which dynamic changes in the atmosphere can make changes in sea ice that are not necessarily expected."
Read more at the University of Washington.
Sea ice image via Shutterstock.