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Objectives of the Report

This report deliberately focuses first on the most obvious and immediate solar forcing of that part of the Earth's environment where life exists, where understanding solar influences on global change is most important to human welfare and which must thus have high priority. Chapters 2 and 3, therefore, concentrate on solar influences on temperature and composition of the lower layers of the Earth's atmosphere. Chapters 4 and 5 assess solar forcing of higher atmospheric layers and of the Earth's near-space environment and the possible coupling of this forcing to the biosphere. Chapters 4 and 5 do not attempt an exhaustive discussion of all solar-terrestrial connections; this is left, for the most part, to other studies. Chapter 6 discusses knowledge of solar variability itself. Chapter 7 covers strategies for research in solar influences on global change, and recommendations appear in Chapter 8.

The Working Group on Solar Influences on Global Change met twice, in November 1990 and March 1991. Since then the topic has been the focus of three meetings: a Workshop on Solar-Terrestrial Impacts of Global Change, sponsored by the High Altitude Observatory in Boulder, CO, in May 1991; an international symposium on The Sun as a Variable Star: Solar and Stellar Irradiance Variations, International Astronomical Union, Colloquium No. 143, in Boulder in June 1993; and a NATO Advanced Research Workshop on The Solar Engine and its Influence on Terrestrial Atmosphere and Climate, in Paris in October 1993. Proceedings of these three meetings are in preparation. Significant effort has been made to include in this report the relevant results reported at these meetings and in the scientific literature, as of June 1994.