environment and identify their information needs. This research should address particular beliefs about global change as well as how people evaluate probabilistic and uncertain information and how they combine multiple bits of information from experts, mass media accounts, and personal experience (e.g., with recent weather or air pollution events) to form their judgments about the extent and seriousness of global environmental problems. Such research will require both intensive methods of interaction with informants and survey methods.

Research effort should also be devoted to studying the expert judgment of environmental analysts about global change. This research should address such questions as: Does professional training encourage or discourage particular misperceptions? Does it lead purportedly independent experts to share common preconceptions? How well do the experts understand the limits of their knowledge? Do estimates of the human effects of global change take into account feedbacks among human systems? In analyses of possible responses, what responses are likely to be omitted? To whom do experts turn for analyses of feasibility of responses? What implicit assumptions about human behavior guide the analyses? With preliminary answers to such questions, it is possible to estimate the sensitivity of analyses to variables that affect expert judgment and therefore to make better informed interpretations of these judgments.

Aggregated Individual Responses

The consequences of global environmental change often depend on the aggregated responses of very large numbers of individuals. The example of U.S. energy conservation shows the effect of millions of decisions to buy more fuel-efficient automobiles, reset thermostats, and reinsulate buildings; millions of consumers also drove down sales of aerosol cans when the news got out that they were releasing CFCs harmful to the ozone layer (Roan, 1989). Action to block UV-B radiation from the skin of a billion light-skinned people would similarly take many discrete actions by each of them.

As U.S. energy conservation efforts demonstrate, such individual actions are multiply determined. Financial considerations motivate action, but structural constraints limit action (for instance, not owning the home one would like to insulate); personal attitudes and values increase the likelihood of taking actions that fit the attitudes, subject to the other constraints; specific knowledge

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