Page 81

heritage. But scientists also must learn how disparate, entire systems of species live and react to changes in their habitats and especially to changes in the concentration of CO2. The effect of combined CO2 enrichment and greenhouse warming on the mix of species and other attributes of natural communities cannot be determined without field research conducted over many years.

Strengthen research on social and economic aspects of global change and greenhouse warming. (pp. 70–71)

The U.S. research program has emphasized issues of atmospheric chemistry, climate modeling, and monitoring, while relatively little attention has been given to issues of impacts, mitigation, and adaptation. Major priorities should be (1) improved understanding of the costs for mitigating greenhouse gas emissions, particularly in the energy sector, (2) more detailed studies of the impacts of and adaptations to climate change, (3) a better understanding of the social and economic processes generating greenhouse gas emissions, (4) policy analysis of options and strategies relating to climate change, and (5) improvements in the data base for understanding economic and environmental trends relating to global change.

Greenhouse warming is a global problem; therefore it will be important to encourage interdisciplinary and international programs. Thorough analytical studies of the impacts of greenhouse warming currently are limited to a few relatively high income countries. Yet it is the poor countries, with a large fraction of their population and output in the farm sector, who are the most vulnerable to climate change. In the research areas listed above, it will be important to examine behavior in developing countries as well as in hihg-income countries like the United States.

Evaluating Geoengineering Options

Undertake research and development projects to improve our understanding of both the potential of geoengineering options to offset global warming and their possible side effects. This is not a recommendation that geoengineering options be undertaken at this time, but rather that we learn more about their likely advantages and disadvantages. (pp. 54–61

Several geoengineering options appear to have considerable potential for offsetting global warming and are much less expensive than other options being considered. Because these options have the potential to affect the radiative forcing of the planet, because some of them cause or alter a variety of chemical reactions in the atmosphere, and because the climate system is poorly understood, such options must be considered extremely carefully. These options might be needed if greenhouse warming occurs, climate sensitivity