It’s shaping up as an “extreme” week for global warming junk science. On Monday, the media reported about a new global warming study with headlines like UPI’s “More Extreme Weather Predicted.”

By Wednesday, Hurricane Wilma was labeled as the “strongest Atlantic hurricane ever reported,” which no doubt will fuel claims that global warming is causing more intense hurricanes.

We can, however, weather such global warming alarmism with the pertinent facts.

Monday’s news was generated by a study published in the Proceedings of the National Academy of Sciences by Purdue scientists who used a combination of mathematical models, historical weather data and local climate systems to supposedly predict that the interaction of increasing greenhouse gas concentrations and local geographic features will increase the frequency and severity of extreme weather events, such as floods and heat waves.

The first red flag, here, is the Purdue researchers’ reliance on a mathematical model of global climate — essentially the Purdue scientists’ crude guess as to how our exceedingly complex climate system works.

While scientists and engineers often can use mathematics to successfully explain how many natural and artificial systems function — where success can be determined by how well the model’s results match up to real-world data — successful climate modeling has so far proved to be too difficult to achieve. Richard Lindzen, the Alfred P. Sloan Professor of Meteorology at MIT, says that the models fail to correctly describe the behavior of clouds, which may cause predictions of higher temperatures to be three times too high.

In fact, no mathematical climate model has ever been validated against the historical temperature record. So why would anyone believe that climate models can predict future climate with any reasonable certainty?

Although the Purdue study claims that increasing greenhouse gas emission levels will lead to more extreme weather events, a look at the historical record seems to refute the claim.

During the 20th century, for example, atmospheric levels of carbon dioxide reportedly have increased by about 25 percent, from roughly 295 parts per million (ppm) to 370 ppm, with about two-thirds of the increase occurring after 1950. Based on the Purdue researchers’ claims, we should then have expected to observe more extreme weather in the U.S. after 1950. But this hasn’t been true in terms of temperatures.

During the 20th century, 26 states recorded their record low temperatures before 1950. Only 17 states recorded record high temperatures after 1950. So the post-1950 acceleration in greenhouse gas concentrations doesn’t seem to have any effect on the occurrence of extreme temperatures.

There’s little reason, then, to have confidence in the claims of the Purdue researchers.

Turning to Wilma — and the inevitability that some will try to link her with the dreaded global warming — real-life data again ought to defuse the alarmism.

Since it’s generally agreed by climate researchers that manmade greenhouse gas emissions haven’t caused an increase in the frequency of hurricanes, global warming advocates now claim that manmade greenhouse gas emissions will lead to stronger, or more “intense” hurricanes. Such claims have been made most recently in studies by the Massachusetts Institute of Technology’s Kerry Emanuel (Nature, Aug. 4) and the Georgia Institute of Technology’s Peter Webster (Science, Sep. 16).

Emanuel claimed in his paper that hurricane strength doubled over the last few decades. But as Virginia state climatologist Pat Michaels recently pointed out, if Emanuel’s claim were true, then “the change would be obvious; you wouldn't need a weatherman to know which way this wind was blowing. All of these feuding scientists would have agreed on the facts long ago.”

National Hurricane center expert Chris Landsea told the Chronicle of Higher Education (Sept. 8) that Emanuel’s results are an artifact of the mathematical procedure he used to derive his claims. When looked at properly, the hurricanes of the past two decades aren’t unprecedented, according to Landsea.

Webster claims in his paper that the number of severe hurricanes (Categories 4 and 5) has just about doubled since 1970. But Michaels looked under the pre-1970 stone and found that Webster was only telling half the story.

Michaels says that during the 25-year period before 1970 the trend was toward fewer strong storms.

“When taken as a whole, the pattern appears to be better characterized as being dominated by active and inactive periods that oscillate through time, rather than being one that indicates a temporal trend,” wrote Michaels.

And as far as Wilma being the “strongest” hurricane on record, chief meteorologist for weatherunderground.com and former Hurricane Hunter flight meteorologist Jeff Masters told Reuters that similar storms could have occurred before the 1960s.

“Back then we didn't have satellites and we didn't have aircraft reconnaissance. So it's quite possible that a lot of those hurricanes [were as strong, or stronger than Wilma].We just weren't around there to see,” said Masters.

If global warming science were like the kids’ game Rock-Paper-Scissors, real-life climate data would trump crystal ball-like mathematical climate models every time. We just need to be on guard so that hysteria isn’t allowed to trump the facts.

Steven Milloy publishes JunkScience.com and CSRwatch.com, is adjunct scholar at the Cato Institute, and is the author of Junk Science Judo: Self-defense Against Health Scares and Scams (Cato Institute, 2001).

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