This research was conducted by the Pacific Northwest Laboratory (PNL) for the Division of Carbon Dioxide Research within the Office of Basic Energy Sciences, U.S. Department of Energy (DOE). The overall purpose of this research was to assist DOE in developing methods for assessing the direct and indirect economic impacts due to the effects of increases in the ambient concentration of CO 2 on agricultural production. Specifically, the primary obj ec t i ves were:• To determine what economic methods and models have been developed or need to be developed to assess the direct and indirect economic impacts of CO 2 -induced environmental changes in the agricultural sector of the U.S. economy .• To provide information and recommendations which will enhance DOE's efforts to assess the direct and indirect economic impacts associated with CO 2 buildup, not only as they relate to the agricultural sector, but to other sectors of the U.S. economy as well.Several tasks were required to accomplish these objectives. First, a comprehensive literature search was undertaken to determine what types of models and methods have been developed, which could be effectively used to conduct assessments of the direct and indirect economic impacts of CO 2 buildup. Specific attention was focused upon: (1) models and methods for assessing the physical impacts of CO 2 -induced environmental changes on crop yields, (2) national and multi-regional agricultural sector models, and (3) macroeconomic models of the U.S. economy. The second task of this. research involved a thorough investigation of the research efforts being conducted by other public and private sector organizations in order to determine how more recent analytical methods being developed outside of DOE could be effectively integrated into a more comprehensive analysis of the direct economic impacts of CO 2 buildup. The third and final task of this research involved iii synthesizing the information gathered in the first two tasks into a systematic framework for assessing the direct and indirect economic impacts of Co 2 -induced environmental changes originating in the agricultural sector of the U.S. economy.The major findings of this research are listed below.• It is anticipated that the direct economic impacts of CO 2 on the agricultural sector and the indirect economic impacts caused by spillover effects from agriculture to other sectors of the economy will be pervasive; however, the direction and magnitude of these impacts on producers and consumers cannot be determined a priori.• Existing agricultural sector models can be effectively linked to macroeconomic models of the U.S. economy to assess the potential scope and magnitude of the economic impacts associated with CO 2 -induced environmental changes that originate in the agricultural sector.• Because of the time frame involved, it is highly unlikely that any type of economic analysis will be able to predict these impacts with any reliable degree of confidence at this time; however, existing models and methods can be used at this t...