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variations on all time scales. Included are paleoclimate investigations involving records in tree rings, and ice cores, as well as Sun-weather relationships. Funding for the core program in this area is diminishing, however, and will need greater emphasis to strengthen the terrestrial component of the program. NSF lists three programs as part of its global change initiative; Coupling, Energetics and Dynamics of Atmospheric Regions (CEDAR); Geospace Environmental Modeling (GEM); and Radiative Inputs of the Sun to Earth (SunRISE).

DoD also has extensive research activities in solar and space physics. These activities involve both theory and ground and space based observations (both from short term research and long term monitoring points of view). The relevance of solar variability for DoD research is that its effects on the Earth environment must be properly taken into account in military operations and particularly in communications and surveillance. A requirement for operational models of upper atmosphere variability to track and predict satellite trajectories, and of ionospheric variability that affects communications, has led DoD to support, over the past decade, what exists today of upper atmosphere research, focusing especially on the solar influences that determine both its neutral and ion composition. The recently implemented Strategic Environmental Research and Development Program (SERDP) encourages use of DoD resources for global change research. In this regard, the Defense Meteorological Satellite Program could provide regular access to space for solar monitoring and global change endeavors.

Because solar influence on global change is a distinctly cross-disciplinary endeavor, cooperative research by DoD, NASA, NSF, and NOAA is essential for mutual benefit to both the USGCRP and the individual agencies. The research effort is hampered by the lack of a lead agency in this area. One challenge to the U.S. program of research into solar influences on global change is to develop a strategy for agency leadership and coordination in pursuing the overall national effort.

International Apects

Two programs within the International Council of Scientific Unions (ICSU) relate to solar influences on global change. One is the Solar-Terrestrial Energy Program (STEP) of the Scientific Committee on