By Richard Romano on January 18th, 2012
As I write this, it is 3°F here in Upstate New York, with a “wintry mix” about to roll in. Ask anyone in the Northeast about the harshness of last winter (especially yours truly, whose snowblower broke as a result of it), and you’ll get a prolonged series of sighs at best, and long streams of lurid profanity at worst. Weather is not climate, of course, and there is a fallacy in interpreting one particular nasty (or, conversely, mild) winter as illustrative of any long term trend. Still, Florida had a remarkably bad winter in 2010, and ask anyone in the UK about December 2010 (again, yours truly happened to be in England when a freak snowstorm shut down the country—and, more specifically, train service whilst I was mid-journey).
That all said, a new study offers a compelling explanation for the Northern Hemisphere’s harsh winters. Says Science Daily, “increasing temperatures and melting ice in the Arctic regions creating more snowfall in the autumn months at lower latitudes.” The study found enhanced Arctic warming from July to September. As this warming continued through the fall, it enhanced the melting of sea ice. “This warmer atmosphere, combined with melting sea ice, allows the Arctic atmosphere to hold more moisture and increases the likelihood of precipitation over more southern areas such as Eurasia, which, in the freezing temperatures, would fall as snow.” The increased snow then affected the “Arctic Oscillation,” which pushed colder air down to mid-latitude regions, like the U.S. and Canada, producing the colder winters.
“We show in the paper how using the snow cover in a seasonal forecast can provide a more skilful or accurate forecast,” said Judah Cohen, lead author of the study, which is published in the latest Environmental Research Letters. “Without correctly simulating the coupling of winter climate patterns and the variability of snow fall, the models currently used by Government centres miss an important influence on winter and will therefore continue to be deficient in predicting winter weather on seasonal time scales, and even longer decadal time scales.”