While the deep freeze we experienced may seem like proof that global warming is a myth, the truth is exactly the opposite, according to scientists who predicted this type of extreme weather in a study published in September. Three scientists from Atmosphere and Environmental Research, Lexington, Mass., and one from Harvard co-authored an article in Oceanography that directly correlates melting Arctic Sea ice with extreme winter weather conditions on continents south.
"Arctic sea ice plays an important role in modulating surface conditions at high latitudes, and even small changes in sea ice extent can cause Arctic climate to change dramatically, with ensuing feedbacks on the entire Earth climate system," the study says. The "ensuing feedbacks" result in part from distorted a jet stream pattern, the so-called "polar vortex." Normally it's a circular pattern around the pole that helps contain the region's chill. Distort the pattern and the chill spills south and can turn into a vicious cold snap anywhere in the northern hemisphere.
A seesaw effect of warm Arctic Ocean weather translating into colder weather on the northern continents has long been observed. However this Arctic Oscillation, as it is termed, has been notoriously difficult to predict. What the study found is that diminishing sea ice in the fall is a clear indicator of mild Arctic winters and, therefore, a warning of severe winter weather elsewhere. Basically, the loss of sea ice exposes darker ocean water, which absorbs more heat, multiplying the effects of the warming that cause the melt in the first place. The warmer ocean is simultaneously more exposed to the atmosphere, where the sea ice would normally keep the ocean waters bottled up.
The added moisture can create more abundant snowfalls elsewhere, and the increased heat creates new convection patterns that help disturb the polar vortex.
Kemo D. 7