To model the effects of climatic variability, one must simplify a very complex system of human-environment interactions. Numerous conceptual modeling schemes have been previously proposed to portray the interactions of human systems and climate variability. We rely here on a scheme modified from one proposed by Kates (1985). Kates's general scheme is shown in Figure 5-1, and our scheme, which focuses on the major factors affecting the human consequences of climatic variations and forecasts, is in Figure 5-2. Our scheme differs from the more general one in providing more detail on particular kinds of human activity and human-environment relationships and in omitting some of the feedbacks in the general model for a more focused presentation.
Most analyses of the human consequences of climatic variability include one or more elements of the scheme in Figure 5-2, with some parts better represented than others. Climatic averages and variations affect various biophysical systems on which people depend; they also influence human activities designed to cope with climate. The human consequences of climatic variations are shaped by climatic, biophysical, and social factors, including both the coping activities and more general social forces. For example, farm income is affected not only by climatic events and their biophysical consequences, but also by the coping behaviors of farmers