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Posted by on Feb 11, 2010 in Politics, Science & Technology | 38 comments

Weather is not Climate: What the Bad Winter Storms in the U.S. Northeast Have to Do With Global Warming

Jon Stewart had a nice bit last night on the bad winter weather in the northeast, poking fun at those, mostly on the right, who think that all the snow is evidence that global warming is a myth.

The fact is, weather is not the same thing as climate, and a single weather event doesn’t really tell us anything meaningful about climate, let alone global climate. This is simple enough to understand, isn’t it?

I won’t repeat what I’ve written many times before — e.g., here, here, and here — but the gist is this: Climate changes on a global level can lead to all sorts of freakish weather. Indeed, in a world that is warming, winter storms like the one ravaging the northeast will continue to happen — and may be partly attributable to global warming. Here, via TNR’s Brad Plumer, is meteorologist Jeff Masters:

There are two requirements for a record snow storm:

1) A near-record amount of moisture in the air (or a very slow moving storm).
2) Temperatures cold enough for snow.

It’s not hard at all to get temperatures cold enough for snow in a world experiencing global warming. According to the 2007 Intergovernmental Panel on Climate Change (IPCC) report, the globe warmed 0.74°C (1.3°F) over the past 100 years. There will still be colder than average winters in a world that is experiencing warming, with plenty of opportunities for snow.

The more difficult ingredient for producing a record snowstorm is the requirement of near-record levels of moisture. Global warming theory predicts that global precipitation will increase, and that heavy precipitation events–the ones most likely to cause flash flooding–will also increase. This occurs because as the climate warms, evaporation of moisture from the oceans increases, resulting in more water vapor in the air.

And here’s Brad with some additional points:

Now, that doesn’t mean we can definitively blame this snow monstrosity on global warming — again, it’s hard to attribute any single weather event to long-term climate shifts. (For instance, El Niño may be playing a bigger role right now in feeding these storms.) At most, we can say that a warming climate will create the conditions that make fierce winter storms in the Northeast and mid-Atlantic more likely. Or at least it will for awhile: If the planet keeps heating up, then at some point freezing conditions in the Northeast will become very rare, at which point snowstorms will, too But we’re not at that point — the Earth hasn’t warmed that much yet.

On the other hand, climate models do predict that snowstorms in the southernmost parts of the United States should become much rarer in the coming decades: There’s plenty of moisture down south, but freezing temperatures are likely to decrease and the jet stream is expected to shift northward. So if those regions start seeing a sustained uptick in snowfall, then something’s gone awry in climate predictions. But the blizzard in the Northeast, while miserable and incredibly disruptive, doesn’t appear whack with long-term forecasts.

(For more, see Bryan Walsh at Time.)

All this is science, though, and, of course, the global warming skeptics and denialists, like the various talking heads on Fox News, don’t want anything to do with science, with truth and the search for truth, with reality. For them, it’s about sticking their heads out the window, once they remove them from their backsides, and basing everything on a) how they feel, and b) what fits their partisan political ideology and narrative.

“Oh, look, it’s snowy, it’s cold… Al Gore is wrong!”

Stupid, stupid, stupid.

And extraordinarily dangerous. We disregard what our world is telling us at our peril. And, in refusing to deal with what is going on, with what an overwhelming consensus in the scientific community is telling us, we put not just ourselves in peril but also future generations that will have to deal with our willful negligence.