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Actually, Weather Is Climate

It is statistically appropriate to point to this year's frigidity as evidence that the theory of man-made global warming is suspect.

by
William M. Briggs

Bio

January 22, 2010 - 12:00 am
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Sure is cold out there, unusually so. By “unusual,” I mean the temperature is on the low end of the observed temperatures from previous winters.

Of course, we don’t have any more than about 100 years of reliable measurements, so it’s possible that the freeze we’re experiencing now isn’t as unusual as we suspect. But, anyway, it still sure is cold.

If you recall, a lot of global warming models predicted it would be hot and not cold, and to risk redundancy, it sure is cold. Does this dissonance between the models’ predictions and what is actually happening mean that those models are wrong?

No. But it sure as ice doesn’t mean that they are right.

Here’s the thing: No matter how cold the winter is, no matter how much snow falls, the global warming models will not be disproved. In technical language, they cannot be falsified by the observations.

Another way to say this is that the winter we’re seeing is consistent with what the models have been predicting. Again — does this consistency mean that the models are right and that the theories of man-made warming are true?

No.

Consistency is such a weak criterion that almost any imaginable theory of climate will produce predictions that are consistent with observations. The term is probabilistic: It means that what actually happens had to have some chance of occurring according to a model. If global warming climate models said, “It is impossible that this winter will see temperatures below X,” and temperatures did, in fact, drop below this threshold, then the models would be inconsistent with the observations. The model would be falsified.

But global warming climate models never make statements like that. They say that any temperature is possible, even if this possibility is low. Certain temperatures have probabilities as low as you like, but they are never precisely zero. (To anticipate an objection: “that number was practically zero” is logically equivalent to “she was practically a virgin.”)

Man-made global warming is just one of many possible theories of climate. Another is the Business-as-Usual Theory (BUT), which states that whatever happened last year will more or less happen this year, and so on into the future.

The winter we’re seeing is consistent with the BUT, which like the man-made global warming theory, never says any temperature is impossible. Further, BUT is corroborated more strongly by this winter than is the man-made warming theory. BUT’s predictions are closer to what we actually see.

“Stop right there, Briggs! You’re making the classical mistake of confusing weather with climate. The global warming models make predictions of climate and not weather. This winter doesn’t mean anything!”

I am not making that mistake, and it is you who are confused. Weather is climate. More specifically, aggregations of weather are climate. Means, averages, and distributions of daily weather comprise climate. That is, climate is a statistical phenomenon and depends for its existence on defining a reference time frame.

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