Writing in the New York Times, University of Washington professor Cecilia Bitz sounds a four-klaxon alarm about the rapidly-warming Arctic:
In late February, a large portion of the Arctic Ocean near the North Pole experienced an alarming string of extremely warm winter days, with the surface temperature exceeding 25 degrees Fahrenheit above normal.
These conditions capped nearly three months of unusually warm weather in a region that has seen temperatures rising over the past century as greenhouse gas concentrations (mostly carbon dioxide and methane) have increased in the atmosphere. At the same time, the extent of frozen seawater floating in the Arctic Ocean reached new lows in January and February in 40 years of satellite monitoring.
In recent years, the air at the Arctic Ocean surface during winter has warmed by over 5 degrees Fahrenheit above normal. So was this recent spate of warm weather linked to longer-term climate change, or was it, well, just the weather?
What we can say is this: Weather patterns that generate extreme warm Arctic days are now occurring in combination with a warming climate, which makes extremes more likely and more severe. What’s more, these extreme temperatures have had a profound influence on sea ice, which has become thinner and smaller in extent, enabling ships to venture more often and deeper into the Arctic.
This coincides with an article in the Washington Post describing new research that the unusually cold and snowy winter just ended in the Northeast U.S. and in Europe is a direct consequence of warmer Arctic weather:
The study, titled “Warm Arctic episodes linked with increased frequency of extreme winter weather in the United States,” shows that severe winter weather, late in the season, has increased over the eastern United States since 1990 as the Arctic has dramatically warmed, faster than any other part of the world.
When the Arctic is warm, the study finds, cold weather and heavy snowfalls in the eastern United States are two to four times more likely than when it is cold.
“This paper argues that the weather was cold not in spite of climate change but likely because of climate change,” said Judah Cohen, lead author of the study.
As Arctic temperatures have warmed in recent decades, late winter weather severity has increased in the East while decreasing in the West, the study found.
Because the increase in winter weather severity in the East has been most pronounced in February and March, when the biggest winter storms tend to form, major East Coast cities have seen an uptick in the frequency of crippling snowstorms. “We found a statistically significant increase in the return rate of heavier snowfall in Boston, New York and Washington,” Cohen said.
Scientists haven't found the exact causes of the relationship, but evidence for the correlation got a lot more significant this year. But the prediction that anthropogenic climate change would lead to a feedback loop and rapidly-warming Arctic, in combination with extreme weather events elsewhere at the same time, has been around for decades. We're now seeing the predictions come true.
In other words, we're going to experience harsh winters in places that haven't had them for a few years, before the ocean becomes so warm that weather patterns shift again, probably suddenly (i.e., within a couple of decades). We don't know what the next pattern will look like. But we can predict it will be more extreme, and that beachfront property in the mid-Atlantic looks like a bad investment.