This volume represents the culmination of a major effort to review the state of scientific understanding concerning the potential effects and impacts of increasing carbon dioxide (CO2) concentrations. All sections of this volume (including the outline) have been subjected to an extensive peer review process. In addition to guidance provided by the editor's panel of reviewers (listed in the book), the American Association for the Advancement of Science (AAAS) arranged for external peer review of the outline, individual chapters, and the assembled volume following chapter revisions.