January 09, 2007
|Explaining This Winter's Warmth||Environment|
NOAA announced today that 2006 was the warmest year on record in the continental US. Winter weather has been especially anomalous: in much of the US, winter has never really arrived.
RealClimate, the premier climate science site on the web, tackles the obvious question: what's causing the anomalous winter warmth? Is it global warming?
First, a couple of maps. This was the situation a year ago, when winter temperatures were also unusually warm:
The map shows how much temperatures last winter differed from average temperatures for the baseline period 1971-2000 (a period that was already warmer than usual).
Here's the situation so far this winter:
Last year was warm, but this year is ridiculous. Where I live, for example, average temperature has been 12-14 degrees F warmer than the baseline.
The scientists at RealClimate are quick to make the obligatory disclaimer that no single weather event or season can be chalked up to anthropogenic (human-caused) global warming (AGW). Variations and anomalies occur for a variety of reasons.
But, that said, the non-AGW explanations don't seem adequate to explain the magnitude of this winter's anomaly. Some meteorologists say El Niño is to blame, but, according to RealClimate, El Niño, which shifts the path of the jet stream, typically changes winter temps in the Northern Hemishphere by about 1 deg C. The current anomaly, they say, is roughly 5 times greater. Moreover, the current El Niño event is only of moderate strength. Besides which, AGW may itself be behind El Niño:
It is possible, in fact probable, that climate change is actually influencing El Niño (e.g. favoring more frequent and larger El Niño events), although just how much is still very much an issue of active scientific debate.
So one cannot say definitely that AGW is the culprit — but no other explanation seems adequate.
The RealClimate scientists take particular issue with the Fox News argument that Denver blizzards somehow disprove AGW:
A canard that has already been trotted out by climate change contrarians (and unfortunately parroted uncritically in some media reports) holds that weather in certain parts of the U.S. (e.g. blizzards and avalanches in Colorado) negates the observation of anomalous winter warmth. This argument is disingenuous at best...[T]emperatures for the first month of this winter have been above normal across the United States (with the only exceptions being a couple small cold patches along the U.S./Mexico border). The large snowfall events in Boulder were not associated with cold temperatures, but instead with especially moisture-laden air masses passing through the region. If temperatures are at or below freezing (which is true even during this warmer-than-average winter in Colorado), that moisture will precipitate as snow, not rain. Indeed, snowfall is often predicted to increase in many regions in response to anthropogenic climate change, since warmer air, all other things being equal, holds more moisture, and therefore, the potential for greater amounts of precipitation whatever form that precipitation takes. [Emphasis added]
So, as we noted in an earlier post, the anomalous blizzards in Colorado, far from being a refutation, are entirely consistent with — in fact, predicted by — models of global warming.
> But, that said, the non-AGW explanations
> don't seem adequate to explain the
> magnitude of this winter's anomaly. Some
> meteorologists say El Niño is to blame,
> but, according to RealClimate, El Niño,
> which shifts the path of the jet stream,
> typically changes winter temps in the Northern
> Hemishphere by about 1 deg C. The current
> anomaly, they say, is roughly 5 times greater.
But global warming has only warmed the globe about 1 F since 1900. By your reasoning, that also does not imply a global warming factor behind recent northeastern warming.
I think you are stretching the facts and inappropriately dismissing others in order to reach the conclusion you want. (Which is that global warming is an apocalpytic problem. You definitely have a penchant for apocalyptic thinking.)
Posted by: Doug at January 9, 2007 04:50 PM
> So, as we noted in an earlier post, the
> anomalous Blizzards in Colorado, far
> from being a refutation, are entirely
> consistent with — in fact, predicted by — models > of global warming.
This is complete and utter bullshit. No global warming scenario or model has predicted these specific blizzards in Denver. If you are going to claim this, I demand a citation to a scientific paper or study saying exactly that. Produce it--I dare you.
Models of global warming DO NOT predict the weather. Get this in your thick skull. There have been big snowstorms in Colorado for tens of thousands of years. You absolutely CANNOT pin this on global warming. Theories of global warming deal only with statistical, long-term compilations of weather, on the scale of decades.
I want to see the exact scientific paper that *predicts* (your word) the recent blizzards in Colorado. PRODUCE THEM OR SHUT UP AND RETRACT THIS STATEMENT.
You are no better than extremists on the right who deny GW. What you have written is not among the scientific conclusions to which climatologists have come, just as the right's are not.
You are an extremist and your exaggerations are hype which are now serving to discredit legitimate scientific arguments about global warming. You're no better than Michaels, Balling, Idso and Idso, Singer, Baliunas, Soon, and that entire crowd.
I insist: PRODUCE A CITATION TO THE SCIENTIFIC LITERATURE THAT SPECIFICALLY PREDICTS THE RECENT COLORADO BLIZZARDS OR RETRACT YOUR STATEMENT AND APOLOGIZE.
Posted by: David at January 9, 2007 05:01 PM
If you modeled a 10 MPH increase in the speed limit, you would predict more accidents. That is different than SPECIFICALLY PREDICTING a certain pile-up.
Posted by: Kent at January 9, 2007 06:43 PM
I have to admit I didn't see this global warming effect coming. Who could have predicted AGW could actually flare tempers?
Posted by: Jeff at January 9, 2007 06:52 PM
David, get a grip. I wasn't suggesting that GW theory predicted the specific blizzards in Denver, but that it predicts an increase in events like the blizzards in Denver. Sorry if that wasn't clear to you. As cited in the post: "Indeed, snowfall is often predicted to increase in many regions in response to anthropogenic climate change, since warmer air, all other things being equal, holds more moisture, and therefore, the potential for greater amounts of precipitation whatever form that precipitation takes."
Kent's comment says it best.
Posted by: Jonathan at January 10, 2007 09:43 AM
Doug, the argument you cite (that the current anomaly is unlikely to be explained by El Nino since it's five times greater than the usual El Nino effect) was not my argument: I was summarizing the argument made by the climate scientists at RealClimate. If you're at all familiar with their work, you will know that they consistently err on the side of being careful and circumspect in the claims they make.
Posted by: Jonathan at January 10, 2007 10:02 AM
Jonathan, here is what you wrote: "So, as we noted in an earlier post, the anomalous blizzards in Colorado, far from being a refutation, are entirely consistent with — in fact, predicted by — models of global warming."
"predicted by". That was your choice of words. And it is simply scientifically wrong. There have been blizzards in Colorado for thousands of years. What specifically is different about these Dec06/Jan07 blizzards that they are caused by global warming while all the hundreds of others were not?? When and where were they predicted? By whom? You must have a source, since you seem so certain that these blizzards were "predicted."
Posted by: David at January 10, 2007 11:11 AM
David, I'm going to agree with you here. Technically, that one sentence, on its own, may in fact be inaccurate.
I'll also say that if you're going to use a single syntax error, in a single post, on a single blog to make an argument against global warming, you're as narrow sighted as the ignorant fools who tried using the Denver blizzards as an argument against global warming in the first place. It’s been said over and over and over again that no single weather event is proof (or disproof) of global warming. You really need to stand back and get the big picture and stop being so anal-retentive.
Posted by: Jeff at January 10, 2007 03:06 PM
I agree, David, that Jonathan certainly could have been clearer in that last sentence, but I happen to have read it as he had intended—that GWT predicts more frequent anomalous weather events. To my knowledge, there is no scientific work that predicted the Colorado blizzards specifically. That's a straw man argument that comes, intentionally or not, from you.
And golly, between the profanity, the belligerence the shouting and the sanctimony in your original comment, one might get the impression you've been listening a little too much to your much-maligned "extremists on the right."
Posted by: Michael at January 10, 2007 08:16 PM