The United States Government, cognizant of its responsibilities to future generations, has been sponsoring research for nine years into the causes, effects, and potential impacts of increased concentrations of carbon dioxide (C0 ) in the atmosphere. Agencies such as the National Science Foun 2 dation, National Oceanic and Atmospheric Administration, and the U.S. Department of Energy (DOE) cooperatively spent about $100 million from FY 1978 through FY 1984 directly on the study of CO * The DOE, as the 2 lead government agency for coordinating the government' s research ef forts, has been responsible for about 60% of these research efforts. William James succinctly defined our purpose when he stated science must be based upon " ... irreducible and stubborn facts." Scientific knowledge can and will reduce the present significant uncertainty sur rounding our understanding of the causes, effects, and potential impacts of increasing atmospheric CO2* We have come far during the past seven years in resolving some underlyinig doubts and in narrowing the ranges of disagreement. Basic concepts have become less murky. Yet, much more must be accomplished; more irreducible and stubborn facts are needed to reduce the uncertainties so that we can improve our knowledge base. Uncertainty can never be reduced to zero. However, with a much improved knowledge base, we will be able to learn, under stand, and be in a position to make decisions.

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.