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1 introduction As the human race prepares to venture into a new century, conversations and news reports are peppered with references to our "fragile and endangered planet." This phrase almost cer- tainly exaggerates the case. The earth is 5 billion years old, and over the eons it has endured bombardment by meteors, abrupt shifts in its magnetic fields, dramatic realignment of its land masses, and the advance and retreat of massive ice mountains that reshaped its surface. Life, too, has provect resilient: In the more than 3.5 billion years since the first forms of life emerged, biological species have come and gone, but life has persisted without Interruption. In fact, no matter what we humans do, it is undikely that we could suppress the powerful physical and chemical forces that drive the earth system. Although we cannot completely disrupt the earth system, we do affect it significantly as we use energy and emit pollu- tants in our quest to provide food, shelter, and a host of other products for the worId's growing population. We release chem- icals that gnaw holes in the ozone shield that protects us from harmful ultraviolet radiation, and we burn fuels that emit heat- trapping gases that build up in the atmosphere. Our expanding 1
2 INTRODUCTION numbers overtax the agricultural potential of the land. Tropi- cal forests that are home for minions of biological species are cleared for agriculture, grazing, and logging. Raw materials are drawn from the earth to stoke the engines of the growing world economy, and we treat the atmosphere, land, and waters as re- ceptacles for the wastes generated as we consume energy and goods in our everyday lives. Scientific evidence and theory indicate that as a result of such activities, the global environment is undergoing profound changes. In essence, we are conducting an uncontrolled experi- ment with the planet. The changes facing the planet today are distinguished from previous changes by the scale and pace with which they are oc- curring or are likely to occur. Over the geologic past, conditions in Me atmosphere, ocean, and biosphere have for the most part followed natural cycles. Now, human activities are a significant force driving changes in the gIobai environment. This book is intendec! to present briefly the current state of scientific knowledge about the changes under way in the global environment. Its organization, inspiration, anti, to a substantial extent, its content derive from the Forum on Global Change and Our Common Future, which took place in May 1989 in Washington, D.C. (see Appendixes A, B. and C), and which was jointly sponsored by the National Academy of Sciences, the Smithsonian Institution, the American Association for the Advancement of Science, and Sigma '<i, the scientific research society. Speakers at the forum placed the current state of the global environment firmly in the context of the earth system, in which human activity is increasingly viewed as a counterpart to the integrated workings of the atmosphere, oceans, land masses, and biosphere. Humans have long affected their local environment, but it is only in this century, particularly in the last 50 years, that the scope of this influence has expanded to a global scale. Now it is clear that with ceaseless repetition, even seemingly innocuous actions such as driving a car or cutting down a tree can influence the physical and chemical systems that govern the earth. In the ., . ~_ an . e
INTRODUCTION 3 case of the acid deposition that alters soil chemistry and affects the natural chemical balance of many of the world's waterways and lakes, the effects of pollutant emissions in one part of the world can be felt half a continent away. The chIorofluorocar- bons (CFCs) produced and emitted by industrialized countries rise to the stratosphere, where, like other pollutants, they dis- perse without regard to political or geographical boundaries. When forest land is cleared and used for grazing cattle or grow- ing crops, plant and animal communities are disrupted (or, for species with limited habitat, eliminated). Our activities have already caused changes in the compo- sition of the earth's atmosphere, most notably increased atmo- spheric concentrations of trace gases such as carbon dioxide, methane, nitrous oxide, and chIorofluorocarbons. From the be- ginn~ng of earth's history, certain of these trace gases have had an unportant role in the principle that is known as the "green- house effect." In a fashion crudely analogous to the function of Me glass panels of a greenhouse, the gases keep some of the earth's heat from escaping through the atmosphere and thus have the potential to warm the earth's surface temperature. At- mospheric concentrations of carbon dioxide after water vapor the most plentiful greenhouse gas- have increased significantly, mostly because humans have burned vast quantities of fossil fuels In the past 100 years, releasing carbon dioxide in the pro- cess. As forests, which absorb carbon dioxide as they grow, are cleared and the feDed trees and brush are burned or decay, the massive amounts of carbon a forest ordinarily stores are released to the atmosphere. If rapid warming of the earth's surface from changes in the composition of the atmosphere occurs as scientists warn is within the realm of possibility-other global and regional changes could result. Sea level could rise as ice caps melt and Me ocean expands from the extra heat, and agricultural belts will shift. Forests and other ecosystems may be torn apart as both plant and animal groups respond to vastly altered temperature and hydrological conditions, and as various kinds of plants adjust differently to increased carbon dioxide levels. Rapid
4 INTRODUCTION changes in climate could cause regional food shortages, cre- ate waves of environmental refugees, and threaten the security of other countries as the effects of the turmoil ripple through the world economy. This is not to say that all changes will be bad. Some northern high-latitude regions could witness increaser} agricultural yields and benefit from a warmer climate. With the physical, chemical, and biological changes in the earth system that humans are causing, more surprises like the discovery of the antarctic ozone hole cannot be ruled out. At- mospheric chemists point out that despite years of study, no one predicted that a hole would form each year in the protective ozone layer high in the atmosphere over Antarctica. Unexpected events of comparable or greater gravity are likely to continue to appear even as scientific understanding evolves. "Nature seems to be running a fever. We are the flu," ob- served William Ruckelshaus, former head of the U.S. Environ- mental Protection Agency, at the Forum on Global Change and Our Common Future in May 1989. "Our goal is not so much to manage the planet earth as to make ourselves less like a pathogen and more like those helpful bacteria that dwell in our own guts." - -r The transformation of the global environment is driven by ever-greater numbers of people, increasing economic develop- ment, and its attendant increase in industrial activity and con- sumption of energy by humans. Of these factors, population growth is the most easily quantified. Since 1900, the number of people has more than tripled. In 1987, the 5 billionth member entered the human family. Our numbers are increasing today by about 90 million per year, and, according to United Nations (U.N.) projections, are expected to reach 10 billion or more by the end of the coming century. Ninety-five percent of these people will be born in the poor countries of today's developing world. While population has increased, so have standards of liv- ing for many of the earth's people, consumption of fossil fuels, and expansion of the world economy. These changes have al- lowed astonishing improvements in human welfare, but at a
INTRODUCTION 5 cost. Unfortunately, many of the processes that produce gains degrade the environment and deplete the ecological capital the soils, forests, species, fisheries, and water resources-on which humanity relies. People in the richer, developed countries, with only one quarter of the worId's population, consume most of the worId's energy. They command about 80 percent of the worId's wealth, use most of its natural resources, and generate the most waste. Most of the greenhouse gases and chemicals that are changing the composition of the atmosphere and thus contributing to the projected climate change and to other changes such as acid deposition have been emitted by inclustrialized nations in the Northern Hemisphere. People in the developing countries, with three quarters of the worId's population, have less than one quarter of the wealth. But the millions of poor people in the developing world also con- tribute to resource depletion anct environmental stress. The poor and hungry are often compelled to destroy their environment- by cubing down forests and depleting soils in order to survive. In the developing world, improved standards of living can break the cycle of rapid population growth and the environ- mental hazards it engenders. The experience of country after country has shown that economic development, when paired with better opportunities for employment and education, even- tually leads to lower birth rates. The catch, as Ruckelshaus noted at the forum, is that, "If the four-fif~s of humanity now in developing nations attempts to create wealth using the meth- ods of the past, at some point the result will be unacceptable world ecological damage." Developing countries now account for about one quarter of all greenhouse emissions. If the same roads to prosperity are followed that were taken in the past by developed nations, this share could double by the middle of the coming century. The prospect of unchecked global environmental change thus raises troubling questions about equity that world leaders can no longer ignore. Since sacrifice and gain will be unequally distributed, what is the responsibility of the "have" nations that
6 INTRODUCTION created many of the problems to the "have not" nations that seek to develop in order to meet the needs of their people? Is it equitable to expect the poorer nations in their pursuit of Improved standards of living to hold to stringent environmental controls that the developed nations did not have to contend with in their periods of rapid industrial growth? And what is the responsibility of people now living to future generations? The existing disparities between We rich countries of the North and the poor countries of the South and the lack of capital and infrastructure in poor countries to cope with rapid changes in environmental conditions are prompting John Holdren, of the University of California at Berkeley, Jessica Mathews, of the World Resources Institute, and many other prominent political analysts, world leaders, and politicians to reconsider the na- ture of possible future threats to world peace and security. For decades the main threat to security has been widely associated with the potential for conflict between East and West, with the nuclear arms race, and with the U.S./Soviet tensions centered in Central Europe. In the late 1980s, as epochal changes in Cen- tral Europe forced the world to rapidly revise its perceptions of the nuclear threat, the potential risks arising from changes in the global environment began to ciann attention. "The poten- tial explosion of tensions deriving from global environmental change is clearly going to be aggravated by the widespread perception that the biggest burdens will fall on the developing countries of the South and Mat the principal culprits in gen- erating these problems, through both action and inaction, are in the developed countries of the North," said Hoiciren at the forum. International dialogue that is currently under way rep- resents the opportunity for nations~eveloped and developing alike to overcome these tensions and attack together common concerns about the global environment. The future of the global environment and the consequences of the changes in store assumed new currency, at least within political circles, in 1987 when the World Commission on En- vironment and Development issued its path-breaking report, Our Common Future. (The World Commission is also known as
INTRODUCTION 7 the Brundtiand Commission after its chairperson, Gro Harlem BrundtIand, former Prime Minister of Norway isee Afterword, p. 1471.) The commission, created in 1983 by the U.N. General Assembly, was a special independent organization that included representatives from 22 countries, a majority of them develop- ing countries. Over a 3-year period, the members tackled We question tacitly posed by the General Assembly: Is it possible to meet the needs of the 5 billion people alive today without com- prom~sing the ability of future, ever more populous generations to meet their own needs? After exhaustive study and analysis, the commission an- swered with a heavily qualified "yes." The grim but very real prospect that the future of humanity depends on an environ- ment ever more polluted, degraded, and devoid of the ecolog- ical resources requires} to ease poverty and hardship could be averted if processes of economic and social development are transformed. The commission invoked the concept of sustain- able development to describe a means by which economic and social progress could be achieved without compromising the Integrity of the environment. Sustainable development is not a new concept, but its promi- nence in Our Common Future has stimulated governments, policymakers, economists, and moralists throughout the world to reconsider its Implications. Of particular interest is the BrundtIand Commission's central theme: the integration of en- vironment and economy. As BrundtIand pointed out in her keynote address to the forum, "Only growth can eliminate poverty and create the capacity to solve environmental prob- lems. But growth cannot be based on overexploitation of the resources of developing countries. It must be managed to en- hance the resource base on which these countries all depend." If this new doctrine is to govern future approaches to growth and development, painful choices will be required in how we exploit resources, direct investments, develop technologies, and organize our Institutions. The wealthy nations must recognize that their continued prosperity depends in part on maintaining the earth's ability to supply food ant] other resources and that
8 INTRODUCTION this in turn requires increased prosperity and security in the developing world. Our Common Future heightened awareness of some widely discussed, and thought-provoking, arguments. One suggestion, for example, is that it may be time to price goods to reflect the environmental costs of their production and use. Gasoline, for instance, might be priced to reflect the costs of the damage that burning the fuel causes through pollution and increased risk of climate change. Likewise, the price of fer- tilizer might reflect the cost of cleaning up the water supplies it pollutes. In addition, Our Common Future suggests that it may be appropriate to restructure institutions to reflect environ- mental priorities. This would mean that environmental aspects of policy would be considered at the same time as questions of economics, trade, energy, and agriculture, and by the same national and international institutions. Environmental agencies would be given more power to redirect policies that now lead to environmental degradation. Economic, trade, and other govern- ment agencies heavily endowed with money and power would be mandated to develop policies that encourage sustainable de- velopment and would be responsible to their governments for the environmental consequences of their policies and budget allocations. The BrundtIand Commission emphasized that if the pace of global change is to be checked, developing countries are likely to need fresh infusions of financial support in the 1990s to pay for efforts to reduce rates of population growth, to restore and maintain natural resources, and to adopt modern technologies that are less polluting than the ones already outdated in the industrialized world. Our Common Future, as well as many political and economic analysts, points out that the question of increased aid cannot be taken seriously until the debt situation is resolved. Debt remains an urgent problem facing developing countries, particularly in Latin America and Africa. The World Bank reports that in 1988 the 17 most indebted nations paid developed nations and multilateral agencies $31.! billion more than they received in aid. As governments, industrialists, scientists, and the public
INTRODUCTION 9 consider the implications of suggestions such as those above, it is increasingly apparent that the decisions that will make these adjustments possible will require tighter connections between science and policy. The earth has already been committed to major environ- mental change in the years ahead. The elevated concentrations of greenhouse gases already emitted through human activity will persist for many centuries, no matter what we do. The chIorofluorocarbons in the atmosphere today will continue to deplete the ozone shield for centuries. Complex tropical for- est ecosystems once cleared can regenerate slowly at best. The magnitude and rate of change will depend on whether societies clecide to act to slow the atmospheric buildup of carbon dioxide and other trace gases, reverse deforestation, and cut pollutant emissions. Steps required to slow the pace of change, and for adapting to it if need be, will be costly, but so may be the costs of inaction. As climatologist Stephen H. Schneider, of the National Center for Atmospheric Research, cautions, if society chooses to wait another decacle or more, "we face a higher risk that we will have to adapt to a larger amount of climate change than if actions to slow down the buildup of greenhouse gases were pursued more vigorously today." In the face of much scientific, social, and political uncer- tainty, encouraging signs abound. Demographers report, for instance, that birth rates in many countries are declining. Forty- nine nations have ratified the Montreal Protocol on Substances That Deplete the Ozone Layer, which calls for a 50 percent re- duction in chIorofluorocarbon production from 1986 levels by 1999 and provides a mode} for cooperation that spans national boundaries and interests. The amount of energy and raw mate- rials required to produce a given amount of goods is decreasing in some countries, including the United States. Scientists can provide information on which to base deci- sions, but whether to act to slow the pace of environmental change is a social judgment, not a scientific one. Among sci- entists there is a broad consensus that even in the face of in- complete or conflicting data, measures to ease adaptation to the
0 INTRODUCTION potential changes, or even to reduce the rate of changes already under way, are possible and advisable. Steps such as improving energy efficiency and developing alternatives to fossil fuels not only would slow the rate of warming but also could buy cru- cial time to study climate change and assess the unpacts. The presidents of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine advised then President-elect George Bush in 1988 that, "While global en- vironmental change cannot be stopped, the pace of change can be slowed. We cannot buy absolute security against environ- mental risk, however much we are willing to pay, but we may be able to reduce environmental damage and risk markedly by prudent policy actions" (see Appendix D). In the encI, the outcome will depend on political will. The social, political, and economic changes would be enormous. Yet government leaders are increasingly attuned to the gravity of the hazards facing society as environmental degradation pro- ceeds. They are talking at the highest levels, and many are struggling to translate acceptance of a set of values, such as the need to protect the environment, into action. In the United States, our environmental statutes are among the most stringent in the world, and the people repeatedly express their desire for increased environmental protection. Yet this country is the largest emitter of greenhouse gases, and environmental pollu- tion continues to be a major problem. The chapters that follow provide the backdrop of scientific information on which the political decisions ultimately will rely. The complexities of earth system science, the lessons derivecl from the earth's history, and the modern forces driving changes in the global environment are explored in the first part of this book, "The Earth as a System." The second part, "The Faces of Global Environmental Change," describes some of the trans- formations projected or under way. These include the prospect of a warmer global climate, potential changes to the worId's food production systems and water supplies as climate changes, and the likelihood that sea level will rise as the climate warms
INTRODUCTION 11 and how this may affect the world coastal zones and their in- habitants. Subsequent chapters examine other human-induced changes to the global environment, including the threat to the earth's ozone layer, deforestation and dwindling genetic diver- si$y, and how acid deposition affects our forests, lakes, and waterways. (Appendix A contains a selected list of additional reacting on global environmental change.) The environmental challenges described are difficult ones for a world already grappling with other costly and more ob- vious problems of economics, security, and public health. But as the following chapters demonstrate, global environmental change may well be the most pressing international issue of the coming century.
