Tuesday, February 23, 2010

Snow job: winter weather doesn't disprove climate change


First in an occasional series.

The Claim

"It's the most severe winter storm in years, which would seem to contradict Al Gore's hysterical global warming theories." -- Sean Hannity, Fox News host

"Historic snow storm in Washington -- third this year -- where is Al Gore to explain it snows this heavily as a sign global warming is imminent." -- Newt Gingrich, former Republican Speaker of the U.S. House of Representatives

The Context

A harsh winter in Washington, D.C., has, predictably, been the source of plenty of Al Gore jokes. Many climate skeptics have held up recent snow storms as evidence that climate change is not actually happening.

The Evidence

First things first -- weather is not climate. But the likelihood of certain weather patterns is determined by climate. What we've seen in the snow-covered middle Atlantic this winter isn't just possible in a warming world, but it was actually anticipated.

Let's go straight to the U.S. Global Change Research Program's very useful synthesis report, Global Climate Change Impacts in the United States. On the subject of winter storms, it says: "There is also evidence of an increase in the intensity of storms in both the mid- and high-latitude areas of the Northern Hemisphere, with greater confidence in the increases occurring in high latitudes. The northward shift is projected to continue, and strong cold season storms are likely to become stronger and more frequent, with greater wind speeds and more extreme wave heights. " (Emphasis ours.)

(The complete article at onearth.org is here).

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