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 The NRC panel should have recognized that much of the work they recommend could be helped by the conscious use of cloud seeding agents, but instead they advised researchers to stay away from applications. When researchers have agents that can change the microstructure of clouds, the use of them during research projects can indicate whether they understand the natural processes. Weare concerned with the NRC' s procedure in the course of such a difficult review process, Only two of the nine committee members had extensive weather modification experience, none in hail suppression. Some had excellent backgrounds in technologies used in weather modification. The committee cited the extent of their interaction with the "community" and listed those participating in one of the report appendices, A few of us on this WMA committee were listed in that community. Our personal experience and those of at least one other modeler listed is that, in some instances, the contact was of the briefest kind, perhaps a phone call to obtain a reference or a passing conversation in the hall at work. Consequently, the appearance of broad community participation in the NRC report is exaggerated, 4.3 Additional WMA perspectives on cloud seeding technology Despite the difficulty in objectively quantifying the absolute values of seeding effects, the large body of positive indications reported by many (see, for example, Todd and Howell (1985)) and other references in this report, and a multitude of analyses in the literature constitute a collective positive signal. Objective consideration of the entire body of evidence, ranging from a-posteriori analyses in operational project reports to carefully designed and conducted research-oriented operations and analyses leads us to the conclusion that cloud seeding, when properly conducted, can, in appropriate atmospheric conditions, have a positive effect on precipitation. This position is supported by one ofthe observations of the NRC report noting an increase in operational cloud seeding programs in many parts of the world in recent years with a dramatic decrease in research funding for such programs. However, we would recommend that research be strengthened to help evaluate and optimize the operational programs. The sponsorship decision to support an operational cloud seeding program can perhaps best be viewed as a risk management assessment, What is the risk of making the wrong decision weighed against the potential benefit/cost ratio? Numerous studies have demonstrated that a 10-15% increase in precipitation can provide sizable benefits to a variety of beneficiaries (irrigated agriculture, hydroelectric production, municipal water supplies) at very favorable benefit cost ratios of 5-1 011 or higher. For example, if a potential sponsor of a cloud seeding program, following careful deliberation, decided they had an 80% likelihood of obtaining a 10% increase in precipitation that would yield a benefit/cost ratio of 1011, they would probably chose to support the program. The other part of the dynamic driving the increase in operational programs, especially those involving precipitation enhancement, is related to increasing populations and either stable or declining (pollution, drought, depletion of ground water, etc.) water supplies. This factor, coupled with the relative ease with which cloud seeding programs can be designed, implemented and operated and stopped without long term commitments 33