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An Ill Wind Blows Toward an Even More Inhospitable Climate

October 30, 2003|Naomi Oreskes and James Fleming | Naomi Oreskes is an associate professor of history and director of the science studies program at UC San Diego. James Fleming is a professor of science, technology and society at Colby College and president of the International Commission on the History of Meteorology.

There's more bad news for those watching the fires raging uncontrollably through Southern California: the prediction that in the years ahead, global warming will intensify our weather patterns, leading to an increase in the droughts and floods to which California is naturally prone. More droughts, in turn, will almost certainly mean more fires; more floods will mean more mudslides.

What can be done? One suggestion, made in a report by the National Academy of Sciences just two weeks before the fires began, was that renewed research be conducted into deliberate "weather modification."

The report calls for a major new national research effort into finding man-made solutions for nature's wrath, such as cloud seeding and rain formation, as a way to alleviate droughts and, by extension, fight fire.

But such grandiose proposals have a long and unpromising history. The fact is, there is no scientific basis for believing that weather modification really works. Moreover, attempts to control the weather are likely to be unpredictable and to have unintended consequences.

Scientific weather modification dates back to the pioneering cloud-seeding experiments of Irving Langmuir, Vincent Schaefer and Bernard Vonnegut at the General Electric Corp. in the 1940s. During World War II, these men and others worked extensively on techniques to create smoke screens, disperse fogs and de-ice combat aircraft. After the war, Langmuir brought these skills to bear on cloud modification and rainmaking.

But this research ran into stiff scientific criticism on the grounds that the experiments were unverified and perhaps unverifiable. Although some cloud-seeding experiments were indeed followed by rain, it was impossible to prove that the rain was caused by the cloud seeding. Given the large number of variables associated with climate and weather, the efficacy of any short-term weather modification program could not be proved. And if the experiments did work, wouldn't they be stealing rain from other areas down-wind? What if they generated bad weather, like hail or tornadoes? Public concern mounted, and in 1946 General Electric halted all outdoor weather modification experiments on advice from legal counsel.

Indeed, some experiments apparently did go awry. In 1947, Langmuir and colleagues, then working with the Army Signal Corps, the Office of Naval Research and the Air Force, seeded a hurricane in the hope of weakening it or redirecting it away from the U.S. coast. The outcome was the opposite, and the hurricane dramatically changed direction within six hours of seeding to make landfall on the U.S. coast.

The fact is, weather modification has never been shown to work in a reliable and controllable way, and the Academy of Sciences report admits as much: "Evaluation methodologies vary but in general do not provide convincing scientific evidence for either success or failure." This has been true for the last 60 years, and it remains true today.

The academy now suggests a new long-range research program in weather modification to sort all this out, although the time frame for meaningful results, the report acknowledges, "may be measured in decades." In other words, we won't know whether weather modification can help solve our problems until 2030, 2040 or beyond.

Meanwhile, according to our best scientific understanding, continued fossil-fuel burning is likely to produce a global temperature rise of 3 1/2 to 9 degrees Fahrenheit by 2050.

The research proposed by the academy will not solve the problems of global warming because the results will come too late to be of use and because any large-scale attempts to modify the climate may go awry. Further scientific research in weather modification may be a worthwhile endeavor, but it is not a meaningful response to global warming. It will do nothing to prevent the tragedies that may be heading our way.

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