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D Leder on Global Environmental Change to President-Elect George Bush from the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine The Honorable George Bush The President-Elect of the United States Old Executive Office Building Washington, D.C. 20501 Dear Mr. President-Elect: The problem of global environmental change is now widely recognized as one of growing urgency that will require re- sponses by your Administration. Our views on the problem and possible responses are attached. Embedded in the diverse manifestations of this problem gIobal warming, ozone depletion, tropical deforestation, and acid deposition-are enormous challenges to science and engi- neering, to your Administration, and to the world community of nations. in many instances, data and analyses are incomplete and long-term effects remain indeterminate; in addition, there are costs to the economy embedded in any decisions made to address the problem. Yet, even with a continuing background of uncertainty, it is important to recognize that human activities are indeed changing the global environment. Prudent courses of 169

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170 APPENDIX D action need to be initiated now to try to understand and predict these changes, and to move toward suitable policy responses. As outlined in the paper that follows, we suggest three principal actions that your Administration can take against the possibility that we may be conducting an irreversible experiment with our planet. First, the issue of global environmental change must be made more prominent in the scientific, political, and foreign policy agendas of the United States. While the issue has been given more emphasis in the past several months, the need now is for sustained and systematic attention to economic and envi- ronmental policies bearing on global change. Second, a focal point for the deployment of national re- sources to address the issue needs to be established to coordi- nate the diverse activities related to the problem. Such activities under way within the government are often poorly coordinated and insufficiently focused on the necessary linkages between scientific understanding and policy options. Further, policies must be such that they enhance the resiliency, robustness, and range of options of the affected sectors, from energy production to agriculture to coastal development. Third, specific actions should be taken by your Adm~n~stra- tion to address those aspects of the problem that are reasonably well understood. Thus, we suggest that you consider the fol- lowing findings and responses: . Both global warming and acid deposition are linked to heavy reliance on fossil fuels. Therefore, efforts to en- hance both energy efficiency and conservation should be strengthened; means for increasing the use of the "clean- est" fossil fuels, such as natural gas, should be consid- ered, but In the context of appraising their finite avail- ability; and alternative non-fossil fuel energy sources, such as nuclear reactors and solar energy, need to be reappraised with more emphasis put on their use in a safe and publicly acceptable manner.

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APPENDIX D 171 The Montreal Protocol is an important first step toward controlling stratopheric ozone depletion. However, pro- visions in the Protocol should be called upon to encour- age deeper reductions in emissions of ozone-destroying . . . chemicals with a total phaseout of chlorofluorocarbon products on a reasonable time scale. Global warming will affect sea levels, agricultural sys- tems, forestry, and water resources. It is not too soon to assess possible impacts and responses. Tropical forests are being cut down at an alarming rate. Mitigating strategies that consider the economic and other forces driving this destruction need to be imple- mented in collaboration with the affected nations. Improved predictions of the future course of the global environment require new and innovative approaches to studying the earth and its environment. A substantial in- vestment in research and ground- and space-based mon- itoring activities is needed. This is a broad agenda, and a challenging one. However, we believe that it offers a sensible approach to problems that ur- gently require presidential leadership and whose consequences, if realized, could be severe for all nations. Leadership by the United States could be a powerful force for uniting the nations of the world In a common endeavor vitally Important to all. FRANK PRESS President National Academy of Sciences Yours sincerely, ROBERT M. WHITE President National Academy of Engineering SAMUEL O. THIER President Institute of Medicine

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172 APPENDIX D PREFACE Early in 198S, the Presidents of the National Academies of Science and Engineering and the Institute of Medicine, with the concurrence of their Councils, decided on the preparation of a small number of "White Papers" for the incoming Admin- istration. The intent was to summarize concisely a few critical national and global issues to which science and technology were central, and to suggest presidential options on these issues. Global environmental change emerged at once as a leading candidate for such a paper. Concern about man-made changes in the atmosphere and consequent changes in climate and the ozone shield has been mounting for more than a decade. A broader range of issues, including tropical deforestation and regional degradation in water and air quality, has heightened public awareness. A major international research program to build an integrated base of knowledge to address these problems is taking shape. Thus, an early decision was made to develop a paper on global environmental change, along with papers on presidential science advising, the AIDS problem, and national space policy. Topical outlines of the principal scientific problems and ele- ments of the current scientific consensus were prepared with the aid of the staff and members of various National Research Coun- ci! groups. These outlines were broadly circulated for comment. A revised outline, together with an exploratory draft, provided the basis for a searching discussion by a group of invited senior scientists at an ad hoc meeting held in Boulder, Colorado, on Participants in the ad hoc meeting were C. J. Pings, University of Southern Cal- ifornia (Chairman); James Anderson, Harvard University; Robert Fri. Resources for the Future; Stephen H. Schneider, National Center for Atmospheric Research; Thomas F. Malone, St. Joseph College; William Nordhaus, Yale University; Arthur Johnson, Uni- versity of Pennsylvania; Robert McC. Adams, Smithsonian Institution; Jerry Melillo,

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APPENDIX D 173 August 15-16, 1988. The views elicited in this discussion played a major role in the subsequent development of the paper by the Council groups. The development of the paper was coordinated by John S. Perry and Ruth S. DeFries of the staff of the NRC Committee on Global Change and by Norman Metzger of the NRC Executive Office. Woods Hole Oceanographic Institution; and Sir Crispin Tickell, United Kingdom Am- bassador to the United Nations.

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74 APPENDIX D GLOBAL ENVIRONMENTAL CHANGE Human activities now match or even surpass nature as an agent of change in the global environment, as evidenced by a growing list of seemingly diverse human-induced environmen- tal changes that have gripped public attention In recent years: . rapid changes in the global atmosphere due to fossil fuel combustion and industrial activities predicted to change global climate; . massive ozone depletion over the Antarctic and lesser decreases over the rest of the globe, both attributed to emissions of chiorofluorocarbons; large-scale destruction of tropical forests for timber, fuel, conversion to agriculture, and economic development, with consequent additions to the "greenhouse" effect and losses in plant and animal species; damaged lakes in New England, Canada, and Scandi- navia associated with acid deposition from fossil fuel combustion. Although the full long-term implications of these changes are as yet unclear, there is a growing perception that the future welfare of human society is to an unknown degree at risk. Our current scientific understanding amply justifies these concerns, but also presents opportunities for effective presidential leadership and action. Recent events have illustrated the possible social, economic, and political implications of future global environmental change. Widespread droughts in the early 1970s set the stage for major worldwide fluctuations in grain prices. Damage to lakes and forests has created major political tensions in North America and Europe. Continued droughts in Africa have stressed the aid and relief machinery of the developed nations of the north.

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APPENDIX D 175 The inctividual environmental problems that have come to public attention are intricately and inescapably interlinked, both scientifically and politically. Scientifically, their resolution re- quires an understanding of the physical, chemical, and biolog- ical processes that govern the earth, and of the interaction of these processes in the entire earth system. Politically, policy options to address these problems converge on the need for internationally accepted actions relating to energy, technology, land use, and economic development. Their implementation will require U.S. commitment and the development of improved mechanisms for international collaboration. Such issues challenge political leadership. The conse- quences of global changes to indiviclual political constituencies are probably several clecades away, unclear in nature, but po- tentially serious. Remeclial and adaptive actions are likely to be expensive in the short term, whereas their full benefits may be enjoyed only by future generations. Many possible courses of ac- tion in policies relating to research, energy, development, and in- ternational relations involve multiple and interlinked costs and benefits transcending both national and generational bouncts. Such problems can only be assessed, and prudent long-term response policies can only be effectively developecl, at the high- est political levels. Global change is quintessentially an issue for leadership at the level of heads of state. The United States, in your presidential term, is well positioned to play a world leadership role. WHAT ACTIONS ARE SUGGESTED? It is now timely to consider prudent policy actions in three areas: prevention, adaptation, and research. These actions, which can only be set in motion by presidential leadership, are dis- cussed below, followed by synopses of the current scientific un- derstancting of the components of global environmental change of current concern.

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76 APPENDIX D Preventing Global Environmental Change We are already irrevocably committed to major global change in the years ahead. The elevated concentrations of green- house gases produced to date by human activities will persist for many centuries and will slowly change the climate of the earth, regardless of our actions. The chIorofluorocarbons (CFCs) that are depleting the ozone shield have lifetimes on the order of a century. Complex tropical forest ecosystems have the ability to regenerate, but this depends on the way they are managed, and regeneration will occur slowly at best. While global environmental change cannot be stopped, the pace of change can be slowed. Put another way, we cannot buy absolute security against environmental risk, however much we are willing to pay; but we may be able to reduce environmental damage and risk markedly by prudent policy actions outlined below. Energy Policy Production of energy from fossil fuels is the root of several of the agents of global environmental change, notably climatic change and acid deposition. There has been great concern, and considerable remedial action, with respect to emissions of sul- fur and nitrogen compounds from fossil fuel combustion. More- over, reductions in fossil fuel combustion address the continuing concerns for regional air quality and acid deposition, the grow- ing concerns for global climate, and our growing dependency on foreign energy resources, i.e., petroleum. To prepare for the possibility that the use of fossil fuels (par- ticularly coal) may need to be recluced in the years ahead, we should explore means for reducing energy demand without impeding economic growth, for example, by using fossil fuels with greater eff~- ciency, as well as incentives and other means to increase use of the "cZeanest"fossiZfueZs such as natural gas. However, the finite avail- ability of natural gas, a premium energy source and valuable chemical feedstock, also needs to be considered. The potential

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APPENDIX D 177 for energy efficiency gains and fuel-switching is demonstrated by the responses to the energy price shocks of the early 1970s. A vigorous research and deveZopment program should give in- creased emphasis to energy sources that do not produce carbon dioxide. New technologies for publicly acceptable nuclear reactors-so- called "safe reactors" should receive attention in an R&D pro- gram on alternative energy sources. Geothermal, wind, solar, and other renewable energy sources warrant reexamination to see if recent progress has improved their economic feasibility as possible substitutes for fossil fuels in the years ahead. Actions by the United States alone, while setting a good example, would in themselves be only marginally effective in slowing the rate of global carbon dioxide emissions. In the decades to come, major demands for energy will come from the developing nations. These nations will have to evaluate the needs of their own economic progress together with protection of the global environment. Thus, energy policy issues are likely to be on the international political agenda. Policies to Reduce I:ndustriaZ Emissions The Montreal Protocol to limit emissions of CFCs, signed in the fall of 1987 by 31 nations including the United States is an unprecedented example of international cooperation to prevent global environmental deterioration. The provisions of the Montreal Protocol comb be called on to urge deeper cuts in the production of CFCs, to accelerate the timetable for their reduction, and to urge aZZ countries to sign and enforce the Protocol. Technology exists to eliminate most of the industrial emis- sions that cause acid deposition. The use of clean, low-sulfur coal and combustion and cleaning technologies can significantly reduce emissions in power plants. However, some emission- control techniques may be energy-intensive, thus increasing car- bon dioxide emissions, and may produce solid and liquid waste products that are difficult to deal with. Thus, policies to con- trol acid deposition involve trade-offs with measures to address other environmental problems, and often require international

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178 APPENDIX D coordination. In any case, there are political and economic com- ponents in any decision on dealing with acid deposition; and to date such decisions have been deferred by the past two Admin- istrations in favor of more research. We believe that the sources of acid cleposition, the technology to limit emissions, and the as- sociated costs and political risks are now sufficiently understood that further deferral in favor of more analysis is unwarranted. Development Policy The future course of a number of the global environmen- tal issues discussed above will be strongly influenced by the manner in which the economies of the less developed nations evolve over the next several decades. A nation's impact on its own environment, and on that of the globe, clearly depends on its population level, standarcl of living, and the technologies used to support that standard. Uncontrolled growth of popula- tions in developing countries seeking better standards of living with inefficient technologies can only lead to continued damage to the local anct global environments. Development aid policies shoul~focus on improving the indigenous scientific and technoZogicaZ knowledge base and infrastructure of the deveZoping countries as a foundation for environmentaZZy sustainable economic development to address these nations' aspirations for a better life. Development aid decisions should include a consideration of environmental impacts. Adapting to Global Environmental Change If we do no more than slow the pace of environmental change, thus gaining time to deal with its effects, we will have achieved much. Policy options to enhance our ability to cope with environmental change should therefore also have high pri- ority. Because the detailed evolution of the expected changes cannot at present be predicted, policies should seek to enhance the resilience, robustness, and range of options of the sectors likely to be affected. For example, the likelihood of rising sea levels should clearly be taken explicitly into account in the planning of coastal development, construction of port facilities, location of waste

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APPENDIX D 179 disposal dumps, and so on. Possible changes in the frequency and severity of extreme events floods, droughts, and severe storms- should also be considered. The possibilities for signif- icant changes in regional hydrology should be considered in planning for major water-resource projects. Better understand- ing of the response of crops and natural vegetation to changes in climate and atmospheric composition is needed. The already impressive adaptability of agriculture may be further enhanced by investments in the development of improved crop strains, the exploitation of new crops, and technology for improving water utilization. Options for adaptation are numerous for rich, technologi- cally advanced nations such as ours, but fewer for poor nations. It will be in the interests of all to assist the poorer nations in reducing their vulnerability to environmental change by devel- oping an effective range of adaptations. Improving Understanding of Global Environmental Change We still lack sufficient scientific understanding to predict confidently the detailed evolution of global and regional change in the environment. Obtaining this knowledge will require strong support for research already under way, nationally and in- ternationally, and support for new long-term programs of interdis- ciplinary, international research. Monitoring global change will involve coordinated, long-term observations, both from space and on the ground. Long-term commitments must be made for resources that will make uninterrupted observations possible over the decades to come. The acquisition of knowledge through research and moni- toring is expensive, although not nearly as costly as the possi- ble consequences of ignorance. We are already investing large resources in the study of the earth, but these efforts require augmentation and coordination.

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180 Institutional Needs APPENDIX D However, current institutions and mechanisms in govern- ment and in the scientific community both in our country and in the international communi~need strengthening to assure a strong scientific program for unclerstanding the global envi- ronment and developing timely, well-coordinated, and effective policies. The existing mechanisms for coordination between govern- ment agencies are not adequate to address the complex scientific and policy implications of global change. Mechanisms exist within the federal government that couIct play a major role in directing the massive and diverse resources of government on this problem; notably, the interagency Com- mittee on Earth Sciences of the Federal Coordinating Council on Science, Engineering, and Technology. However, effective direc- tion of these governmental resources cannot be achieved solely by the normal processes of interagency coordination. Even more complex issues are posed by the need for collaboration between sovereign nations. Effective leadership and direction in this area is clearly required. The issue of global environmental change must have a prominent place on the scientific, political, and foreign policy agendas of the United States. PRINCIPAL SCIENTIFIC ISSUES The policy recommendations suggested above are shaped by our current understanding of the various aspects of global environmental change, particularly by the considerable uncer- tainties in our knowledge. Reducing these uncertainties would lead to more informed and effective policy decisions. Climate Change A central issue in global environmental change is the ef- fect of changing atmospheric composition on global climate. The greenhouse effect the trapping of the sun's heat near the earth's surface by small concentrations of certain gases in the

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APPENDIX D 181 atmosphere has been well understood since the eighteenth cen- tury and is arguably the most firmly established principle in atmospheric science. These "greenhouse gases" include water vapor, carbon dioxide, methane, and the CFCs. in the nineteenth century, marked growth in carbon dioxide concentrations began from about 280 parts per million (ppm) in 1850 to 350 ppm today. This increase can be explained by the burning of vast quantities of fossil fuels, the massive conversion of carbon-rich forests to farmland and pasture, and the absorp- tion of about half of the emitted carbon dioxide in the ocean Today, fossil fuel use injects about 5 billion tons of carbon into the atmosphere each year, and deforestation adds at least ~ bil- lion tons more. As a result, carbon dioxide concentrations are continuing to increase at about 0.4 percent per year. Other greenhouse gases are also increasing. Methane, emit- ted from of! and gas wells, rice paddies, bogs, tundra, and increasing populations of creatures ranging from cows to ter- mites, is increasing at over ~ percent per year. The principal CFCs, despite recent limitations, are still increasing at several percent per year. Other gases such as nitrous oxide and tropo- spheric ozone are similarly increasing. The combined effect of each year's increase in these gases is roughly equal to that of the carbon dioxide increase alone. , . Estimating the influence of continuing increases in green- house gases on future climate requires quantitative models of the climate system, as well as predictions of how human ac- tions will influence future emissions. Based on our current understanding of natural processes and plausible projections of population growth, technology, and economic development, it is expected that before the middle of the next century the com- bined effect of increases in all greenhouse gases will produce an impact on the climate roughly equivalent to a doubling of preindustrial levels of carbon dioxide alone. Numerical models of the climate system yield estimates of the effect on long-term global mean temperatures that range between ~ and 5C (2 to 9F). The rate of climate change implied by these estimates is as much as 100 times greater than the average rate of change since

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182 APPENDIX D the last glacial period (when global temperatures were about 5C cooler than today and ice sheets covered our northern tier of states), and about 10 times greater than the fastest known sustained climate change during the last 10,000 years. Recent observations of increased temperatures are consistent with predicted changes, but we clo not yet know if they actually confirm that greenhouse warming is indeed in progress. Incli- vidual disastrous climatic events, such as a dry summer or a vigorous hurricane season, cannot be attributed to greenhouse warming. The expected rapid rate of climate change greatly compli- cates the task of predicting the changes most important to hu- man society the timing and regional distribution of changes, and the frequency and severity of extreme events. Warming shoulc! lead to worldwide changes in many features of the hy- clrological cycle, with consequences for soil moisture, river flow, glacier extent, and the distribution of crop zones. In addition, there are reasons to expect that warmer ocean temperatures will lead to more violent tropical storms. The detailed consequences associated with this expected warming are still unclear. Complex changes In temperature, precipitation, soil moisture, and storm patterns could result in a web of economic impacts. Climatic zones and storm tracks may be expected to shift poleward. Crop zones and natural ecosystems can be expected to migrate with the changing climate, although the extent of movement is uncertain. Major shifts could clearly have far-reaching economic, social, and political consequences. Melting of land-borne glaciers and thermal expansion of sea water are expected to raise global sea levels signifi- cantly over the next century. Projections of the amount of rise range from tens of centimeters to as much as 3 meters, with reasonable estimates centering on a ~ meter rise. Rising sea levels will increase the already trouble- some rates of coastal erosion and loss of wetlands, while .

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APPENDIX D . . . . 183 increased saltwater intrusion would impair water sup- plies and agriculture in coastal areas. Warming is expected to be considerably greater in polar latitudes than in the tropics, and sea ice should diminish. A navigable Arctic Ocean would have major national security implications. Changes in rainfall patterns are likely, and some studies indicate greater summer dryness in midlatitude conti- nental regions. Regional changes in water supply and quality may have significant economic and social conse- quences. Adverse climate changes may be difficult to accommo- date in developing countries, where resources are not available to adapt to changing conditions. Growing pres- sures for migration may result. implications for human health may result from changes in the range of disease vectors (e.g., insects and rodents) and in the frequency and intensity of extreme weather known to influence mortality rates. There is a disturbing possibility for surprises as the climate system rapidly changes. The record of the past, notably as revealed by ice core records, shows that the climate system can exhibit large and rapid changes in response to slow changes in natural forcing. Today, humanity is imposing new stresses on the system, raising the question of possibly triggering climatic . . . surprises ~ our own hmes. Tropical Deforestation Tropical forests are being rapidly destroyed because of the pressure of growing local populations for agricultural lanct and fuel wood supplies, and the strong world markets for tropical hardwoods and animal products from tropical pastures. Satel- lite data provide reasonably reliable estimates of the rates of deforestation; if these rates continue, the planet will be virtually denuded of tropical forests early in the next century. This massive change in the earth's vegetation has many

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184 APPENDIX D consequences. As noted above, the associated carbon dioxide release adds about 20 percent to the release from fossil fuel com- bustion. Other troublesome gases such as nitrogen oxides and ozone are also produced directly or indirectly from burning to clear land. Deforestation can also lead to long-term degraciation of soil fertility, anct is intricately linked to significant changes in regional hydrology and climate. Perhaps the most serious long-term impact of tropical deforestation is the loss of plant and animal species. This loss of genetic resources may rob us of valuable options for future resources for food, industry, and health. Many of these changes are irreversible, and the full range of their long-term consequences is poorly understood. Stratospheric Ozone Depletion Ozone is naturally produced in the stratosphere by the inter- action of sunlight with oxygen. Although present only in small concentrations, it blocks out highly damaging solar ultraviolet radiation, and is thus essential to life. Observed ozone concentrations (a few parts per million) are maintained by a balance between ozone production and natu- ral ozone-destroying chain reactions involving extremely small concentrations of nitrogen, hyclrogen, and chlorine compounds. The CFCs, synthetic chemicals widely used in industry and con- sumer products, are known to enter the stratosphere, where they provide a new primary source of chlorine. This relationship be- tween surface release of CFCs and global stratospheric ozone loss was identified in 1974. The discovery of the Antarctic ozone "hole" the abnor- mal depletion of ozone over the entire Antarctic continent in the early Southern Hemisphere spring-was brought to world atten- tion in 1985. In the last 2 years, ground-based and high-altitude aircraft experiments have indicated that the ozone depletion is related to CFC concentrations, and laboratory experiments are clarifying our understanding of the mechanisms involved. Small worldwide decreases in total ozone have recently been detected through careful analysis of surface-based and satellite

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APPENDIX D 185 observations. These changes amount to a few percent, and vary markedly by latitude and season. Such systematic long-term declines in ozone are accompanied by large natural seasonal and interannual variability, which can mask underlying trends. The best understood implications of stratospheric ozone de- pletion lie in human health. Changes in total ozone of 5 percent in the middle latitudes would raise ultraviolet radiation levels at the surface enough to increase skin cancer incidence by more than 10 percent. Immunological changes also may result from ultraviolet exposure. Effects on plants and animals are poorly understood, although there are grounds for concern. Effects on food chains in the world ocean, with ultimate effects on fish harvests, as well as effects on agricultural crops and natural systems are also likely but have not yet been assessed. Acid Deposition Fossil fuel combustion in power plants and in autos pro- cluces oxides of sulfur and nitrogen, which are converted to acids in the atmosphere. These compounds are transported in the atmosphere over long distances and are responsible for re- duced visibility and increased deposition of acids on the ground across large regions. Increased deposition of acids in forester! areas of the north- eastern United States, Canada, and northern Europe that have low-alkalinity waters and thin, acid soils has resulted in the acidification of surface waters, sometimes to the extent that they no longer can support normal fish populations. The link- age between fossil fuel combustion and acidification has been demonstrated. Acid deposition may be considered as one aspect of a chang- ing "global chemical climate," with many varied and interTinked effects. For example, changes in the "chemical climate" have ac- celerated the corrosion and erosion of buildings and historic monuments. A serious concern is the possibility that changes in the deposition of nitrogen and sulfur compounds have signifi- cant effects on forest productivity. However, the full impact of

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186 APPENDIX D acid deposition and other pollutants on forest productivity and its relationship to the decline of some North American, Cana- dian, and European forest species is not fully unclerstood, and the mechanisms of forest damage are not clearly established. Another aspect of the changing chemical climate is increased concentrations of ozone at ground level, resulting from reactions between nitrogen oxides, hydrocarbons, and sunlight. Ground- leve! ozone increase has also been implicated in human health problems and significant crop losses. Although the degree of increase is uncertain, ambient levels of ground-level ozone in the summertime have been associated in experimental trials with a loss of growth and altered physiological function of forest trees. Finally, ozone in the lower atmosphere acts as a greenhouse gas, and the effects of a changing chemical climate on biological processes undoubtedly influence the fluxes of other greenhouse gases as well. As a final comment, we believe that global environmental change may well be the most pressing international issue of the next century. The United States is well positioned to play a leadership role in coping with and gaining an international consensus on this difficult issue. Indeed, the United States in the past has had a major role in examining the problem whether through the carbon dioxide measurements done on Mauna Loa, the analysis and development of the experimental evidence for the relationship of the Antarctic ozone depletion and CFCs, the substantial contributions of American scientists to creating mathematical models of climate, or United States leadership on the Montreal Protocol.