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 same standards of assessment as planned weather modification, they would have to conclude "that the limitations and uncertainties ofthe models and the lack of physical evidence, and the inability to assess cause and effect statistically, leads one to conclude that there is no convincing proof that human activity is affecting weather and climate". Indeed, if the NRC panel were to hold inadvertent weather modification and climate change theories to the same high standard, they could only conclude that there is "no convincing scientific proof" for either. This having been nOled, there is convincing scientific evidence of positive effects in several areas of weather modification, which will be cited below. The NRC report, in its conclusions, quoted a statement from an NRC 1964 report, stating that the initiation of large-scale operational weather modification programs would be premature. We believe that this is a political statement made by a scientific panel with little recent experience or background in operational weather modification programs. Even the scientist who has asked for better scientific proof has encouraged the continued pursuit of cloud seeding programs where they are scientifically and operationally appropriate (Silvennan, 2003, p 1227), In any event, this panel believes it to be inappropriate for a national scientific panel to make such judgments on a technological industry that has been in existence for nearly fifty years and has provided much scientific evidence, much of it in the refereed scientific literature, concerning weather modification and cloud physics, The recent NRC report leaves much to be desired in a review of research and operations in weather modification. This is not unexpected, inasmuch as the NRC committee had no members from the operations community and lacked depth in weather modification research. The absence of expertise in hail suppression and orographic cloud seeding was especially notable, as was the lack of experience in the modeling of cloud seeding effects. These deficiencies resulted in a report that emphasized the NRC committee's expertise, i.e., experience in weather modification through the 1970's, convective cloud seeding via hygroscopic seeding methods, and the advances in instrumentation that bode well for future research projects. In the following review we discuss the basis for hail suppression, the capabilities in cold season cloud seeding projects, some additional information on summertime cloud seeding projects, the ability of cloud and mesoscale models to simulate weather modification experiments and operations, and other perceived omissions or mis- statements in the NRC review. We close our main response with our conclusions and recommendations. 8