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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
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.