has changed the characteristics of its surface. Excessive destruction of forests and grasslands in conjunction with the urbanization of large land areas has resulted in changes in the surface radiation balance, as well as changes in the fluxes of moisture to and from the surface. Of greater impact on a global scale, have been the direct anthropogenic releases of heat and various pollutants into the atmosphere. These releases have affected the transmissivity of the atmosphere and have changed the radiation balance of the earth-atmosphere system. Although the magnitude of these man-induced changes in the atmosphere has been thus far too small for them to be reliably measured and identified as global climatic changes, it is possible that this situation can change within the next 50 to 100 years. The major human activity that releases pollutants into the atmosphere is the satisfaction of energy demands. Use of fossil fuels as the principal source of energy has been the major anthropogenic contribution to the steady increase of atmospheric carbon dioxide (CO2) levels. Additionally, fossil fuel utilization has contributed to the increasing global levels of atmospheric aerosols. Both CO2 and aerosols play important roles in the radiation balance of the earth-atmosphere system and thus can substantially affect global climate. Many atmospheric models predict that the increasing use of fossil fuels could result in a measurable global climate change by the year 2000 due to increased atmospheric CO2 levels. It has been suggested that, to avoid substantial changes in climate beyond 2000, the use of fossil fuels must be curtailed and other sources of energy must be sought. However, uncertainties still exist about the nature of climate change and the magnitude of man's role in it. These uncertainties effectively prevent the direct consideration of impacts on climate in energy policy decisions at the present. What is certain, however, is that man's contribution to climatic change is a global problem. Thus, any effort to reduce man's inadvertent modification of climate must occur on a global scale and involve the energy policies of all nations. This report has several objectives. The first is to describe the possible anthropogenic contributions to global climate change, particularly from energy production. The current state of knowledge concerning energy and climatic change is reviewed, with particular attention to assessing the unknowns and uncertainties surrounding climatic change and the likelihood
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