I asked Dr. Trenberth to comment on the role climate change has on this latest storm, which is forecast to set records. He explained:
The number 1 cause of this is that it is winter. In winter it is cold over the continent. But it is warm over the oceans and the contrast between the cold continent and the warm Gulf Stream and surrounding waters is increasing. At present sea surface temperatures are more the 2F above normal over huge expanses (1000 miles) off the east coast and water vapor in the atmosphere is about 10% higher as a result. About half of this can be attributed to climate change.
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That final point is very important. The worst deluges have jumped not merely because warmer air holds more moisture that in turn gets sucked into major storm systems. Increasingly, scientists have explained that climate change is altering the jet stream and weather patterns in ways that can cause storm systems to slow down or get stuck, thereby giving them more time to dump heavy precipitation (see my recent literature review here).
The National Climate Assessment noted that this “remains an active research area” but pointed out that: “Heavier-than-normal snowfalls recently observed in the Midwest and Northeast U.S. in some years, with little snow in other years, are consistent with indications of increased blocking (a large scale pressure pattern with little or no movement) of the wintertime circulation of the Northern Hemisphere.”
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In the case of the blizzard bearing down on New England, we have both the extra moisture off the East Coast and an “odd configuration of the jet stream (once again) is moving the low pressure system through a pattern that will create an epic blizzard.”
Read more at The Climate Science Behind New England’s Historic Blizzard
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