past, but other environments preserve some information. Integrated pictures of what the world was like at specific times—for example 5,000, 10,000, or 20,000 years ago—such as those compiled by the CLIMAP and COHMAP consortia can help in understanding how the world has changed. They can also be used to test the usefulness of the models constructed by geophysical fluid dynamicists.

  • Abrupt and Catastrophic Changes in the Past. Episodes of sudden environmental change have been identified from times as recent as 10,000 years ago to 66-million-years ago and more. If we can work out what happened under the peculiar circumstances of those times, it may help in understanding the likely effects of the current changes.

  • Solid-Earth Processes in Global Change. We need a better understanding of how sea level might be changing at present and the effects of volcanism, both above and below sea level, on the global environment. The volume of the ice sheets should be monitored on the decadal scale, and changes in permafrost areas should be observed. Monitoring global change at the surface from space, using the ongoing high-spatial-resolution imagery of Landsat and SPOT-type instruments, is essential for seeing what is happening in such environments as the Sahel, central Asia, and the Altiplano.

  • Present-Day Geochemical/Geophysical Data Base. A global data base of present-day geochemical and geophysical measurements needs to be established for direct detection of future changes. Such data are lacking for remote and underdeveloped regions of the world.

  • Climatic Effects of Volcanic Emissions. The effect on climate modification of volcanic emissions, and their interactions with the atmosphere and hydrosphere, can be better understood from global monitoring of volcanism.

BIBLIOGRAPHY

NRC Reports

NRC (1978). Studies in Geophysics: Geophysical Predictions, Geophysics Study Committee, Geophysics Research Board, National Research Council, National Academy Press, Washington, D.C., 215 pp.

NRC (1983). Fundamental Research on Estuaries: The Importance of an Interdisciplinary Approach, Geophysics Study Committee, Geophysics Research Board, National Research Council, National Academy Press, Washington, D.C., 79 pp.

NRC (1983). Toward am International Geosphere-Biosphere Program, National Academy Press, Washington, D.C.

NRC (1983). Safety of Existing Dams: Evaluation and Improvement, Water Science and Technology Board, National Research Council, National Academy Press, Washington, D.C., 384 pp.

NRC (1984). Studies in Geophysics: Groundwater Contamination, Geophysics Study Committee, Geophysics Research Board, National Research Council, National Academy Press, Washington, D.C., 179 pp.

NRC (1984). Studies in Geophysics: Explosive Volcanism: Inception, Evolution, and Hazards, Geophysics Study Committee, National Research Council, National Academy Press, Washington, D.C., 176 pp.

NRC (1985). Safety of Dams: Flood and Earthquake Criteria, Water Science and Technology Board, National Research Council, National Academy Press, Washington, D.C., 224 pp.

NRC (1986). Global Change in the Geosphere-Biosphere: Initial Priorities for an IGBP, U.S. Committee for an International Geosphere-Biosphere Program, Commission on Physical Sciences, Mathematics, and Resources, National Research Council, National Academy Press, Washington, D.C., 91 pp.

NRC (1986). Studies in Geophysics: Active Tectonics, Geophysics Study Committee, Board on Earth Sciences and Resources, National Research Council, National Academy Press, Washington, D.C., 266 pp.

NRC (1987). Confronting Natural Disasters: An International Decade for Natural Hazard Reduction, Advisory Committee on the International Decade for Natural Hazard Reduction, National Research Council, National Academy Press, Washington, D.C., 60 pp.

NRC (1987). Recommendations for the Strong-Motion Program in the United States , Committee on Earthquake Engineering, National Research Council, National Academy Press, Washington, D.C., 59 pp.

NRC (1987). Responding to Changes in Sea Level: Engineering Implications , Marine Board, National Research Council, National Academy Press, Washington, D.C., 148 pp.

NRC (1988). Space Science in the Twenty-First Century: Imperatives for the Decades 1995 to 2015: Mission to Planet Earth, Task Group on Earth Sciences, Space Science Board, National Research Council, National Academy Press, Washington, D.C., 121 pp.

NRC (1988). Estimating Probabilities of Extreme Floods: Methods and Recommended Research, Water Science and Technology Board, National Research Council, National Academy Press, Washington, D.C., 141 pp.

NRC (1989). Reducing Disasters' Toll: The United States Decade for Natural Disaster Reduction, Advisory Committee on the International Decade for Natural Hazard Reduction, National Research Council, National Academy Press, Washington, D.C., 40 pp.

NRC (1989). Margins: A Research Initiative for Interdisciplinary Studies of Processes Attending Lithospheric Extension and Convergence , Ocean Studies Board, National Research Council, National Academy Press, Washington, D.C., 285 pp.

NRC (1989). Irrigation-Induced Water Quality Problems, Water Science and Technology Board, National Research Council , National Academy Press, Washington, D.C., 157 pp.

NRC (1989). Great Lakes Water Levels: Shoreline Dilemmas, Water Science and Technology Board, National Research Council, National Academy Press, Washington, D.C., 167 PP.

NRC (1990). Assessing the Nation's Earthquakes: The Health and Future of Regional Seismograph Networks, Committee on Seismology, Board on Earth Sciences and Resources, National Academy Press, Washington, D.C., 67 pp.

NRC (1990). Rethinking High-Level Radioactive Waste Disposal: A Position Statement of the Board on Radioactive Waste Management, Board on Radioactive Waste Management, National Research Council, National Academy Press, Washington, D.C., 38 pp.



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