Many of the costs are dispersed, borne by individuals, or not readily valued in financial terms. While most warning systems are clearly cost-effective, costly engineering schemes, such as large reservoirs to increase the food supply through irrigation, are sometimes not. The most effective impacts studies are cooperative efforts among researchers, policy-makers, and the public. The involvement of policy-makers ensures that the research has useful and practical applications for solving real problems. The participation of a broad spectrum of the public, including companies and communities directly affected by the hazard, also improves the project's relevance.
Researchers use a variety of scientific methods to assess sensitivities to climatic fluctuations.
They can review and synthesise the existing research describing climate events and impacts and interview local people, whose knowledge and perceptions of climate hazards can be more detailed and profound than the most sophisticated models. They can conduct individual case studies and field surveys of a specific episode, or a series of studies permitting rigorous comparisons of many different episodes or regions. Finally, they can use quantitative modelling based on simulation, empirical-statistical, or spatial models. Modelling typically requires a great deal of time and effort for collecting the necessary data and validating the results. The most thorough studies use all of these methods together to create as complete a picture as possible.