This volume is written for policymakers and informed citizenry who want to understand at a general level the complexities of global climate change without becoming enmeshed in technical minutia. The introduction emphasizes the core fact that climate change issues cut across disciplines. William Schlesinger and Gerald North explain the carbon cycle and how increased greenhouse gases impact temperature. The economics papers deal with the applicability of benefit/cost analysis and then proceed to examine the benefits of avoiding temperature change versus the costs of the various CO2 abatement options. Finally, David Victor, a Stanford political scientist, asks which policies are feasible in a world where the incentives differ dramatically among countries. The book closes with open letters to the President of the United States.