Recommendations for research and modeling activities for projecting the climatic effects of increasing carbon dioxide

To provide a basis for informed decision making, a capability to accurately project the climatic effects of the increasing carbon dioxide (CO2) concentration and other perturbations is needed. Considering long-term effects, CO2, trace gases, and aerosols have the greatest potential for affecting the climate. Coupling of these factors through chemical. radiative. and dynamical interactions makes the problem very complex. Projections of the climatic effects of the increasing CO2 concentration over the next several decades must consider the combined effects of many simultaneous perturbing factors along with the many feedback processes that are operative. Because of this complexity, we will continue to rely on numerical models as the primary means for making these projections. Improvement of climate modeling capabilities requires a research effort spanning a broad range of activities. The strategy to improve their understanding of climate processes and the capability to project future climate change is based on the use of a hierarchy of models. The research that is recommended for the major areas of scientific investigation is described in the following sections. It is not the intent of this chapter to provide a detailed research plan for accomplishing these tasks. Rather, the purpose of this chapter is to present the overall picture of the major research needs and priorities, highlighting those areas where special emphasis and effort should be directed to address key issues