The Executive Summary describes the goals established by EPS for the study, considering previous work and the Congressional mandate. The analytical framework developed for the study is briefly described and its limitations are noted. Current understanding of the greenhouse gases and their impact on global climate is summarized. A description of the scenarios that were developed to explore the sensitivity of the climate system to policy choices is presented next. The results of this scenario analysis follows, emphasizing the relative impact of various options. The technological and policy strategies that appear most promising for reducing greenhouse gas emissions are then presented by major activity category: energy production and use, other industrial activities, changes in land use, and agricultural practices. The policy options that are available for promoting these emission reduction strategies are then reviewed, giving consideration to the timing of policy responses to the greenhouse gas buildup. Finally, the major findings of the study are summarized.