Weather Mod Critical Issues Report

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I I I I I I I I I I I I I I I I I I I S. Conclusions and Recommendations The WMA has responded to the NRC report concerning issues having operational impact or scientific consequences on operational projects, The WMA strongly supports the NRC's recommendation to establish critical randomized, statistical experiments along with the necessary physical measurements and modeling support to reduce the many uncertainties that exist in the science of weather modification. The NRC panel conclusion that there was no convincing scientific proof that cloud seeding has worked (with a few exceptions), applied a definition of scientific proof that few atmospheric problems could satisfy. On the other hand, the NRC panel concluded, "there is ample evidence that inadvertent weather and global climate modification (e,g., Greenhouse gases affecting global temperatures and anthropogenic aerosols affecting cloud properties) is a reality". Differing levels of proof have been applied by NRC panel to planned weather modification versus global climate change and inadvertent weather modification. A "higher bar" criterion was applied to planned weather modification. The NRC panel cited a much earlier NRC report (NRC, 1964) and concluded that the initiation of large-scale operational weather modification would be premature. We think that it is inappropriate for a national academy panel, with very limited operational weather modification experience, to make such a judgment. Citation of the very dated 1964 report suggests that little has changed since that time. The NRC panel notes operational programs in 24 countries and at least 66 large-scale operational weather modification programs in the V,S. The WMA believes large-scale operational programs have produced and continue to produce positive effects for society. The WMA does not agree with the NRC suggestion that implementation of large-scale operational programs would be premature. WMA's response details many examples of successful operational programs, and provides information on the myriad oftechnological advances that have been made, but that were largely neglected by the current NRC report, This WMA report has added information on hail suppression, winter orographic cloud seeding, summer operational programs, and cloud modeling of cloud seeding effects to fill in for gaps and weaknesses in the NRC report. A few other topics are also commented upon. We support many of the recommendations of the NRC panel, but add several of our own as follows: . We support the NRC recommendation that there be a renewed commitment to advancing our knowledge of fundamental processes that are central to the issues of intentional and inadvertent weather modification. . We support the NRC recommendation that a coordinated national program be developed to conduct a sustained research effort in the areas of cloud and precipitation physics, cloud dynamics, cloud modeling, laboratory studies, and field measurements designed to reduce the key uncertainties that impede progress and 35