How do scientists evaluate environmental knowledge for public policy? Discerning Experts examines three sets of landmark environmental assessments involving acid rain, ozone depletion, and sea level rise, exploring how experts judge scientific evidence and determine what the scientific facts are. The three case studies also explore how scientists come to agreement on contested issues, why consensus is considered important, and what factors contribute to confusion, bias, and error, and how scientists understand and navigate the boundaries between science and policy. The authors also suggest strategies for improving the assessment process. As the first study of the internal workings of large environmental assessments, this book explores the strengths and weaknesses of the assessment process and explains what it can-and cannot-be expected to contribute to public policy and the common good.