Scientists' Uncertainty and Disagreement about Global Climate Change: A Psychological Perspective

Since there are major gaps in scientific knowledge about the greenhouse effect, policy makers are forced to rely on scientists' judgments about the rate of climate change and its effects. It now appears that significant policy decisions will have to be made despite continuing uncertainty and disagreement among scientists. The best that policy makers can do is look for guidance in the best available expert judgment. But when the best experts express great uncertainty and disagree, as seems to be the case with the greenhouse effect, policy makers are unsure about how to proceed. Despite its importance, scientific judgment about the greenhouse effect has not been systematically studied. Psychological research on expert judgment and decision making provides theory, methods, and empirical results that can be used to study judgments based on uncertain and incomplete data and can help to explain the sources of expert uncertainty and disagreement regarding the greenhouse effect. Possible explanations are discussed.