As Boston’s Crazy Snow Keeps Falling, Scientists Weigh In on Climate Impact

If anyone tries to tell you that climate change directly caused Boston’s record-breaking and continuing snowmageddon, that’s not true.  What is true, however, is that climate change may have affected the snowstorm — may have made it more likely, may have made it worse than it would have been without so much greenhouse gas in the atmosphere.  It bears repeating: “All weather events are affected by climate change because the environment in which they occur is warmer and moister than it used to be.”

The question, then, becomes how?  How did the warmer and moister environment in which we now live because of human-caused carbon emissions affect Boston’s historic weather event?  Wouldn’t a warmer, moister environment mean less snow?  How does that even make sense?

Trenberth, who is a senior scientist National Center for Atmospheric Research, offered his explanation via e-mail:

No doubt there is a big element of chance in having the weather pattern of the storm tracks setting up in an optimal fashion to produce big snow storms one after the after.  But in mid-winter, there is plenty of cold continental air to ensure that precipitation falls as snow rather than rain.

At the same time, the environment has warmed especially compared to 1978 (when the last set of major snow storms occurred), boosting the odds of huge amounts of snow.  Part of the warming is from human activities increasing heat trapping gases (carbon dioxide) which have warmed the global oceans. Part is from climate variability (such as from the quiet hurricane season last summer — when all the activity was shifted to the warm Pacific), and the result is sea surface temperatures off the coast exceeding 7°F above normal in parts and 4°F over huge expanses, thereby resulting in 15 to 20% more moisture in the atmosphere.

That moisture gets caught up in the storms, likely invigorating the storms themselves, and the result is major snow storms.

... This explanation would make sense if climate change is helping to intensify the Boston snowstorms, according to Penn State climate researcher Michael Mann, considering how warm sea surface temperatures are off the coast of the northeastern United States right now.  For this time of year, Mann said, sea surface temperatures there are warmer than they’ve ever been.

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