The report discusses different energy sources, fuels, and substitutes in different scenarios to either reduce or control the pollution which causes the greenhouse effect therefore changes the climate of the world. It describes the substitute technologies and other means by which greenhouse gas emissions could be reduced relative to the scenarios described. A range of policies that might be used to promote such reductions are described, which address domestic and international issues. The report discusses the diverse sources and economic activities responsible for greenhouse gas emissions. The primary means of accomplishing the goal of reducing greenhouse gas emissions is the development and use of technologies that reduce energy requirements (i.e., improve energy efficiency), use less carbon-intensive fuels, or that replace or reduce emissions of other greenhouse gases. In addition to this technological approach, there are also several areas in which management strategies are the means of reducing greenhouse gas emissions, particularly with respect to the buildup of gases resulting from some agricultural practices and forest resources.