opportunity not only for seeking out more natural gas supplies but also for applying geology and geophysics to efficient development and production.

  • Developing and testing a new generation of nuclear reactor technology. Understanding the solid-earth will be important for nuclear fuel, waste isolation, and hazard assessment.

  • Accelerating efforts to assess the economic and technical feasibility of carbon dioxide sequestration from fossil-fuel-based generating plants. Efforts in "clean coal" technology have concentrated strongly on high-temperature combustion and related aspects. Solid-earth scientists can identify what coals from what areas can be efficiently used most in the new technology.

Other recommendations relate to forestry, agricultural research, and making the water supply more robust by coping with present variability. Solid-earth scientists through their understanding of the land surface, its drainage, and its groundwater clearly have much to contribute in all basic aspects of mitigation and remediation.

Three Roles for the Solid-Earth Scientist

There are three aspects of global change in which the solid-earth scientist is particularly involved. The first is understanding global change. The record of the past reveals both the extent and the pace of change. This information is useful not only in revealing the extent of past changes but also in showing how fast they have happened and in throwing light on how remote parts of the earth system have accommodated themselves to perturbations. Understanding the approaching changes will be easier if we understand what has already happened. Models of the future can be tested for validity by seeing how well they can reproduce past conditions. The past record is also important in helping to distinguish between anthropogenic change and what is sometimes called natural variability, although the involvement of the human race is hardly unnatural. The role of the solid-earth scientist in increasing understanding of global change is to document the background rates, ranges, and intensities of the environmental kaleidoscope without the factor of anthropogenic changes. That documentation can be obtained in the ways outlined in Chapter 3, The Global Environment and Its Evolution.

The second aspect of global change in which solid-earth scientists will play a part is assistance in reducing the extent of future change. Increasing the world's reserves of natural gas, for example, could make more readily available a fuel that produces less carbon dioxide than most other forms of fossil hydrocarbon. Better understanding of aquifers worldwide could lead to informed management practices less likely to lead to pollution from waste disposal or to depletion of the water supply.

Because the world's population is so large and is continuing to increase, some kinds of global change are inevitable. More coal burning in populous India and China over the next 20 years can hardly be avoided and cannot fail to increase the carbon dioxide content of the atmosphere faster than plausible reductions in carbon dioxide output in the most advanced communities. Some consequent climatic change in the next 50 years appears unavoidable. Because of this prospective change, there is a third useful role for solid-earth scientists in global change research: study of how to mitigate and ameliorate the effects of possible changes. The following examples illustrate how such studies could be effective. Research in areas where sea level is rising today, such as the Gulf Coast where water extraction, reduced sediment supply, and other factors have induced rapid local subsidence, is likely to pay dividends if sea level rise becomes more general in the next century. Research on the hydrology of arid lands—for example, on how transitions from desert to more moist conditions take place—can be carried out now in areas such as the Sahara-Sahel boundary. The results of such studies could prove useful if, as seems not unlikely, there are changes in the distribution of the present climatic zones of the continents in the next century.

At present, models of global change are not capable of suggesting the possible extent of changes in the future, partly because of limited spatial resolution and partly because they cannot accommodate all the controlling variables. Solid-earth scientists have the opportunity to work with other earth scientists, including social scientists, in testing and refining models of the earth system that will be needed for understanding global change sufficiently well to permit informed decision making. The roles of the solid-earth scientist in understanding change, managing change, and mitigating the effects of unavoidable change are all likely to increase in importance in the next decades.

RESEARCH OPPORTUNITIES

The problems and the research discussed in this chapter are concerned with the major interactions



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