Peace Will Give Us a Chance

Anne H. Ehrlich and Paul R. Ehrlich

Given at Berkeley, California, May 7, 1991

The first world war over resources had just been fought in the Persian Gulf. Even though the action was confined to one region, participation was global in scope (at least financially). And while resources have figured in most wars, this conflict was explicitly over access to petroleum deposits, claims to the contrary notwithstanding.

More clearly than any previous war, the Persian gulf conflict also spotlighted the truth of a slogan originated by Another Mother for Peace a quarter century ago:

"War is unhealthy for children and other living things."

Despite United Nations conventions opposing deliberate environmental destruction in war (particularly the Enmod convention of 1977, signed by the United States but not Iraq), such tactics were employed by the Iraqi forces and may have been engaged in by the United States-led coalition as well.1

Among the results was an unprecedented oil spill, many times greater than the 1989 accident in Alaska's Prince William Sound (but smaller than originally reported), which is devastating the fragile marine ecosystem and coastal marshes of the gulf. Perhaps 30 percent of the spilled oil was from Iraqi tankers targeted by Allied weapons;2 the rest reportedly was deliberately released by the Iraqis from shore installations. Oil-coated bird victims (from another spill) were shown repeatedly on television; unseen effects no doubt included the death of coral colonies and much of their associated fish fauna.3 Cleanup efforts were slow to be initiated, and the actual origin of the spill and details of its damaging effects remained unclear months later.

The desert areas of Kuwait and Saudi Arabia, where tanks and other heavy military vehicles maneuvered in training and combat and where fortifications were installed, also were severely damaged. By breaking down the natural crust of the desert surface, the heavy vehicular traffic has exposed the towns and cities of the area to inundation by sand and dust. Countless animals also must have been crushed in their subsurface burrows.4

Most destructive of all may be the detonation of more than 500 Kuwaiti oil wells, an unknown portion of which were set off by Allied bombing. Estimates of the amount of oil being burned have ranged from 1.5 to 6 million barrels per day (equivalent to a range of 8 percent to 32 percent of current U.S. oil consumption). The fires are very difficult to extinguish and will continue producing millions of tons of soot, smoke, and air pollutants (such as nitrogen and sulfur oxides) for many months to come.5 Severe immediate health effects of the air pollution on local populations are already clear, long-term consequences of exposure to it may be serious.6

Possible climatic effects for the region cannot yet be ruled out.7 Black rain was reported early in Iran, along with unseasonably low temperatures beneath the dark smoke clouds. Sharply increased acid rain has been reported from the southern Soviet Union, and soot particles have been detected as far away as the Mauna Loa observatory in Hawaii.8 The potential existed for severe effects on this summer's monsoon in South Asia, home of a billion very poor people, which could have led to crop failures and famine on a scale overshadowing even that caused by the disastrous typhoon flooding of Bangladesh in May. Fortunately for South Asia, prevailing winds shifted by June, blowing the smoke instead over less populated, wealthy Arab nations to the southeast.9

While the war itself appeared to have a successful outcome in terms of Allied casualties (a few hundred), its impact on Iraqi and Kuwaiti citizens has been devastating and socially disruptive in the extreme. Direct Iraqi casualties probably numbered over a hundred thousand. The impact on civilians has also been great, especially in the aftermath; a United Nations investigative team reported that the "near-apocalyptic" destruction of Iraq's infrastructure by Allied bombing had reduced the society to living in medieval conditions.10 Continuation of the embargo against Iraq prolongs and worsens the impact on civilians, who suffer most from lack of food, sanitation, and medical care; estimates of infant deaths from malnutrition and inadequate care range upward of 50,000.

Restoring both Iraq and Kuwait to their former levels of development in terms of infrastructure and basic services will take years, perhaps decades. Fortunately, both have adequate financial resources for redevelopment, thanks to their endowments of oil, but some strain on the world's resources will nonetheless be incurred. 11

Meanwhile, the politically volatile Middle East is far from tranquilized, and even the main political objective - toppling Sadam Hussein from power - has not been achieved, although he has been partially defanged militarily.

From a broader perspective, we fear that the long-term effect of the Persian gulf war may be to continue the diversion of capital, both financial and human, into preparations for war. Indeed, it seems to have given new impetus to the arms trade. Some high technology weapons and weapons systems were glamorized as a result of their perceived success in the conflict. Such weapons are very expensive to build and maintain; their success also was clearly overstated. The attractiveness they gained is already leading to a potential new arms race in high-tech "conventional" arms for export to developing nations and a shot in the arm for the U.S. SDI (Star Wars) program along with some other weapons production programs.12

In short, the Persian gulf war has tended to legitimize warfare as a reasonable means of settling international disputes, rather than helping to raise the world's consciousness that humanity is no longer able to afford that approach.13 George Bush's New World Order looks only too much like the one that prevailed before World War 11; but that was a time when wars caused relatively little environmental damage and casualties were mainly limited to soldiers in combat (which could be horrendous enough). Warfare in the nuclear age, even when fought only with so-called conventional weapons, has the potential to cause unacceptable environmental damage on a regional or even global scale and leads to impoverishment of those who prosecute it (winners or losers). This destructiveness has been evident to anyone who cared to count the costs for decades, but still the lesson seems unlearned in political circles.14

Circumstances that might lead to new conflicts are rife in today's world. Chief among our concerns are the increasing political-economic instability of eastern Europe and the Soviet Union; persistent and deepening poverty, political unrest, and civil war in sub-Saharan Africa; and repression of dissent in China and elsewhere. In the Middle East, beyond the destabilization of the recent war, heightened political-ethnic tensions, and the plight of several million Kurdish and Shitte refugees, rapidly worsening shortages of water are creating tension between nations such as Israel and Jordan.15

All these problems have the effect of promoting conflict and arms races to the detriment of the real sources of any society's security: natural resources (including natural ecosystems), agricultural production, political freedom, and economic stability.16 As humanity hurtles towards a final confrontation with its own life-support systems, people are squandering diminishing resources to fight among themselves for their possession and control. It is a sorry spectacle.

An important (but seldom considered) underlying cause of humanity's conflicts is continued population growth, which diminishes the resources ultimately available for each person. The human population has increased fourfold in this century and is destined to pass 6 billion before the turn of the next one. Demographers tell us that, because of the momentum built into rapidly growing populations, growth is unlikely to halt through humane means (birth limitation) before the population reaches 10 to 14 billion some time in the 21st or 22nd century.17

Accompanying this momentous and unprecedented population outbreak has been an even faster rise in mobilization of energy and resources.18 Worldwide energy use, primarily the burning of fossil fuels, has risen six-fold in only 60 years. Human mobilization of many basic elements and materials now equals or exceeds their natural flows, potentially disrupting or altering the great geochemical cycles on which life depends. The explosive twentieth-century expansion of the human enterprise has caused a similar rise in impacts on the global environments.

The industrial revolution brought a profound shift in humanity's means of support as well as the magnitude of its impact on the planet.19 Previously, human beings had lived mostly within their income - the solar energy received daily at Earth's surface. Food, materials, and energy were all derived from products of photosynthesis, directly or indirectly, with the exception of metals, which can be recycled. The shift to dependence on abundant (but finite) fossil fuel resources to support a burgeoning population marked a change from living mostly on solar income to increasing consumption of humanity's limited supply of inherited "capital." Not only have nonrenewable mineral resources been depleted at increasing rates, but expansion of the human enterprise has led to a progressive degradation of putatively renewable and indispensable resources such as agricultural soils, groundwater, and biotic diversity.

The unsustainable nature of modem agricultural practices has been masked in temperate-zone nations by the success of high-yield seeds, synthetic fertilizers, and pesticides in boosting crop yields in the short term, spectacular though the gains have often been. But continuous plowing and planting of widespread monocultures has led to accelerated soil erosion and a mining of nutrients from productive soils in many areas. Heavy use of farm chemicals leads to serious environmental problems as well. When transferred to the thinner soils and pest-favoring climates of the tropics, however, the vulnerability of industrial fanning becomes apparent.20 But as high-yield crops have spread, traditional varieties have been abandoned, resulting in a narrowing of the genetic diversity of crops. Yet that diversity is the raw material needed for breeding improved crops for the future - especially a future of uncertain climatic stability.21 It is difficult to conceive of a more vital resource for maintaining food security. But efforts to preserve rare crop varieties have not been enough to stem the losses.

The vaunted green revolution of the 1950s-70s has nearly run its course, and no suitable encore is on the horizon that could repeat the record of almost tripled food production since 1950.22 The failure of world agriculture to maintain the per-capita food production levels of the early 1980s lends credence to the suspicion of Lester Brown of Worldwatch Institute, among others, that global food production increases in the 1990s may fall significantly behind the rate of population increase.

Depletion of groundwater resources that are essential to agriculture is underway in many nations, including the United States. The Ogallala aquifer underlying the Great Plains is the best-known example, although a similar story can be told in much of California. Water is being withdrawn from underground sources to irrigate crops at rates far faster than the aquifers can be recharged naturally. In the southern plains and some areas of California - as well as northern India, parts of China, and numerous other semiarid regions - the water table has fallen so far that pumping is no longer economic. Curiously, when the wells were installed in the Great Plains, it was well known that the irrigation systems would be temporary; in western Kansas, they were expected to play out by 2000.

About a third of the world's food is produced on irrigated land today. But irrigation itself can lead over time to degradation of the land through the accumulation of salts or waterlogging. Now, more and more land is being taken out of production as it loses fertility or as aquifers are depleted. Worldwide acreage of irrigated land per person has been falling since 1979.23

The lack of suitable unused land for agriculture to occupy - as well as a shortage of remaining virgin forests and grazing land - indicate how extensively humanity has come to dominate the planet, especially on land. The takeover by the human enterprise of most of Earth's productive land areas, along with overexploitation and damage to oceans and shore areas, is causing the greatest epidemic of species extinctions since the dinosaurs were wiped out 65 million years ago. The destruction of biotic diversity (genes, genetically distinct populations, and species) as a side effect of human activities is among the most serious, although least unappreciated, environmental problems. The last quarter of the twentieth century may see the loss of 10 percent or more of the world's inventory of species as habitats continue to disappear under buildings, highways, airports, and the plow - or are overgrazed or poisoned by various pollutants. A loss of 20 to 25 percent by 2025 is likely, unless a concentrated global effort is made to preserve what habitats remain.24 Of course, unless efforts are also made to avert rapid climate change, even the most strenuous preservation efforts might be in vain.25

Tropical forests are by far the richest reservoirs of biodiversity, containing at least half of all the species on Earth. But tropical forests are under unprecedented assault, vanishing at a rate of nearly 2 percent per year in the late 1980s, twice as fast as a decade earlier.26 Other biotically rich ecosystems are also severely threatened: wetlands, estuaries, coral reefs, subtropical and temperate forests.

Why should we care about the loss of biodiversity? The first reason is that most people appreciate nature or some parts of it esthetically; they enjoy flowers, trees, gardens, and house plants, birdwatching, collecting butterflies, keeping tropical fishes in aquaria, and so forth. Many people also subscribe to the essentially moral belief that other organisms have a right to exist and human beings have no right to extinguish them heedlessly.27

Economics also provides strong arguments; the activities associated with appreciating nature obviously bring economical benefits, but untapped resources still exist in nature that could be of enormously greater economic value. One recent discovery was that the bark of an already rare yew tree in the threatened old-growth forests of the Pacific Northwest contained a substance of value in treating certain cancers.28 Tropical forests in particular have barely been explored as sources of potential foods, medicines, industrially useful chemicals, oils, fibers, and other materials, although their potential is vast and they have already yielded innumerable such items. Indeed, it should be remembered that the very basis of civilization originated in nature's vast genetic library: all our crop and livestock species, medicines, traditional fuels, and materials for clothing, housing, and furniture. To the degree that we heedlessly allow species-rich ecosystems to disappear unheralded, we are in effect throwing away the keys to our future.

But the most compelling reason for preserving natural ecosystems and the organisms that comprise them is also the least understood by the public: they are our life-support systems and provide a series of indispensable free services to civilization.29 These services are mostly taken for granted, although people may notice when they have been damaged or overwhelmed. Nor can society adequately replace or substitute for most of the services; in cases where we might know how to do so, we could not possibly afford it on the required scale.

What are these extraordinary services? First, natural systems help to main min the quality of the atmosphere, including the benign mix of gases present. The oxygen that we are fond of breathing is a product of the activities of photosynthesizing organisms over billions of years. Living organisms have much to do with moderating and stabilizing climates over most of the planet, especially on land. They also help to maintain the balance of greenhouse gases that keep the surface habitably warm (but not too warm). In particular, ecosystems participate in regulating the hydrological cycle which supplies fresh water and is crucial for all terrestrial life (and for agriculture). Forested watersheds recycle rain and retain water, recharging aquifers and releasing surface water slowly and steadily in streams. Loss of the forest often results in increased floods and droughts downstream; streams become less dependable and some even dry up entirely.

Organisms in natural ecosystems also participate in and maintain the natural geochemical cycles that restore vital nutrients to soils and aquatic systems, disposing of wastes in the process. They control the vast majority of pests and pathogens that potentially could plague our crops and ourselves, and pollinate myriad plants (enabling them to reproduce), including numerous crops. Finally, natural ecosystems constitute nature's vast "genetic library" - the inventory of millions of species and billions of genetically distinct populations of organisms from which humanity has already drawn the very basis of its civilization and which could provide undreamed-of future benefits if we have the wit to preserve it.

Far from protecting the integrity of natural ecosystems, however, humanity has taken over the land surface of the planet, replacing natural systems with simplified, artificial ones managed for its own benefit. At some level of exploitation, human beings have occupied or used some two-thirds of the land surface, at least 40 percent of it intensively (as habitation, agriculture, or pasture).

Reflecting this dramatic takeover, some 40 percent of all the potential energy fixed in the process of photosynthesis by green plants on land is being directly consumed by people and livestock, diverted into human-controlled systems (supporting a different set of organisms than would naturally be present), or has been lost as natural systems were convened into less productive ones (forests to farms or pastures; savannas and grasslands to deserts).30 This appropriation and degradation of the energy resource on which human beings (as well as all other animals) are ultimately dependent goes far to explain the epidemic of extinctions now underway, as both living space and food resources for other organisms are lost to human competition. The degree of takeover also indicates a limit to the scope for further expansion of a species that "plans" to redouble its population in the next several decades.31

Environmental problems arising from human activities, once local, or at most regional, in the last decade or two have become global in impact, threatening everyone's security. Human activities pose real dangers of disrupting, perhaps beyond repair, the functioning of the remaining ecosystems through such assaults as stratospheric ozone depletion, widespread acid deposition, and the buildup of greenhouse gases in the atmosphere.

Ozone depletion was recently found to be progressing twice as fast as expected in the northern midlatitudes (which includes most of the United States, Europe, and Japan, and much of the USSR, the Middle East, India, and China) and already causing significant amounts of dangerous ultraviolet-B radiation to reach the surface. As a global problem, the cause of ozone depletion is quite well understood - a limited range of human-made chemical compounds (mainly chlorofluorocarbons - CFCs) released into the atmosphere. It is also clear that responsibility for releasing them rests mainly with the industrialized nations which will be able to supply less damaging substitutes for their principal uses (refrigeration, air conditioning, and as solvents) at minor economic cost. Unprecedented international cooperation in the late 1980s led to a convention to phase out production of CFCs although the recent discovery of escalating damage may require a second acceleration of the timetable.32

The capacity for disruption of natural and agricultural systems by acid deposition, occurring widely in industrialized nations and at least a potential threat in many developing regions, is generally underappreciated. Acidification develops slowly and insidiously, often going unnoticed until exhaustion of a system's natural buffering capacity causes symptoms to appear almost overnight. Aquatic systems are especially vulnerable, and the flora and fauna of thousands of lakes and streams in northern and central Europe and the eastern United States have been severely injured or killed by acidity. Many forests in those regions too have suffered damage, decline, and even complete destruction, largely attributed to gradual acidification, possibly interacting with other air pollutants and natural stresses.33

Much of the world's productive land and many aquatic systems have been severely (and for practical purposes irreversibly) affected, at an annual cost to society of many billions of dollars in damage to agriculture, fisheries, and forests. Even wider areas unquestionably will suffer damage as more and more vulnerable systems succumb to cumulative acidification. While the acid deposition problem has not needed global action, it does require cooperation between nations whose air pollutants have crossed borders and caused damage - such as Canada and the United States and more than a dozen European nations.

Global warming may pose the gravest threats of the three main planet-wide problems, since the climate change that it is expected to induce most likely will affect every part of the planet. Agricultural and natural systems alike are closely adjusted to the prevailing climatic regime in which they evolved; relatively small shifts in temperature and precipitation patterns (which cannot be predicted in detail for particular areas) can be remarkably disruptive. In already decimated natural ecosystems, widespread extinctions and other irreversible consequences may result. Even though climate changes will not necessarily be adverse everywhere, the disruption caused in the short term by the rapidity of change for natural, agricultural, and social systems may at least temporarily overshadow any longer-term benefits. In addition, shifts in climate are unlikely to be one-time affairs; change will be continuous, but possibly not always unidirectional (unless, by some miracle, the greenhouse gas buildup is halted and the system quickly reaches equilibrium).34

Global warming may also be the most intractable global problem for several reasons besides the uncertainties surrounding its progress. One is that it has a multitude of

causes and culprits, being tightly connected to such vital and pervasive activities as energy use (mainly fossil fuels) and agriculture. Every society contributes emissions of the greenhouse gases that are building up in the atmosphere: carbon dioxide and other gases from combustion of fossil fuels or wood; methane and nitrous oxide largely from agriculture and land-clearing; and CFCs.

Obviously, the plethora of greenhouse-gas sources raises many difficult questions of assigning responsibility and greatly complicates the task of reducing emissions. So the policies needed, both to mitigate the effects of warming and adjust to them, will also necessarily be numerous. Fortunately, a start has been made on eliminating CFCs, among the most potent, long-lasting greenhouse gases. Although it was done to protect the stratospheric ozone shield, the greenhouse benefits will be scarcely less valuable.

Excess carbon dioxide emissions are caused mostly by combustion of fossil fuels, but a quarter to a third are considered due to deforestation, primarily in the tropics, an activity that nearly doubled in rate in the 1980S.35 While developing nations have so far made modest contributions to the carbon-dioxide buildup through fossil-fuel-burning, their fast-growing populations and development ambitions, including substantial rises in per-capita energy use, guarantee a growing share of any energy policy change in the rich countries.36

Methane emissions arise not only from combustion but from rice cultivation, flatulence of cattle, and landfills; nitrous oxide releases are associated with fertilizer use and land-use changes. Curbing emissions of these gases in a world with a rapidly growing population with rising food needs will be no easy task.

The diversity of measures required to slow the rate of global warming (thereby allowing adjustments to be made) will have to be implemented through different economic sectors and by governments of all nations which have enormously varying levels of development, wealth, resource endowments, and capacities to carry out policies. Thus important questions about international equity are raised by the complexity of the global warming issue, both in allocating responsibility for causing it and for managing it. Hammering out the Montreal Protocol to phase out CFCs was simple by comparison - and even that has proven inadequate.

With the emergence of global environmental problems demanding global, or at least international, solutions, a new form of interdependence had developed, paralleling that of increasing economic interdependence among nations and the less-appreciated dependencies of the food trade. No society today is sufficiently isolated from the rest that major breakdowns or conflicts can be viewed with equanimity. The world's interdependence now is such that the reduction of Iraq to destitution impoverishes us all.

In this light, the Persian Gulf War, which both highlighted and was precipitated by the global nature of trade in energy resources, was clearly a step backward in building the interdependency that will be increasingly essential for supporting an ever-larger human population. That the war itself, in merely six weeks, caused an unprecedented set of environmental impacts might have brought the message home more clearly - if that information had ever been properly conveyed to the public.37

Nations nevertheless still perceive a need for military power, a perception that it is not independent of the deteriorating resource-environment situation. Even as the chance of a global nuclear war growing out of the East-West confrontation diminishes, the probabilities of regional wars over resources (oil, water) or even environmental issues (acid precipitation, failure to abate greenhouse gas emissions) are rising. Thus the approaching ecological Armageddon could make it increasingly difficult to reallocate resources from military to environmental security. Indeed, the very process of preparing for combat - let alone engaging in it - adds to our environmental peril.38

Environmental security is a life-and-death issue for all peoples; degradation of the human resource base poses threats, at the most basic level, to world food supplies as well as directly to human health and well-being. Worldwide cooperation and reallocation of financial resources far beyond precedent will be required from now on to manage the world's affairs. The world community's principal task of the next century will not only be to deal with the immediate common threats (global warming, ozone depletion, depletion of natural resources, and biotic impoverishment) but also to bring the human juggernaut into balance with its resources and the biosphere. In doing this, the scale of the human enterprise - the size of the population, its global mobilization of resources, the technologies it uses, and their impacts on the biosphere - must be unflinchingly addressed as the underlying driving force behind both the environmental threats to global security and resource-based conflicts.

Recognition is needed that those conflicts only lead to an acceleration of environmental degradation and global impoverishment. Conflicts indeed must be avoided if the means are to be made available to contain the population-resource-environment crisis. People frequently speak of "giving peace a chance." We believe that the wording should be different:

Only peace will give us a chance.


The full name of the Enmod convention is the "Convention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification Techniques." Other applicable agreements include Protocol I of the 1977 Additions to the Geneva Convention of 1949, which prohibits military attacks on the natural environment and on manmade works containing dangerous world forces such as dams, dikes, and nuclear reactors; and the 1982 Charter for Nature, which holds that "nature should be secured against degradation caused by warfare or other hostile activities." The United States has so far not signed either of these two, possibly because they would in effect outlaw the use of nuclear weapons.

Associated Press, March 199 1.

Charles Sheppard and Andrew Price, 199 1, "Will marine life survive the Gulf war?" New Scientist, (9 March, pp. 36-40).

Constance Holden, 199 1, "Kuwait's unjust deserts: damage to its deserts," Science, 251:1175 (8 March) .

Carl Pope, 199 1, "War on Earth," Sierra (May-June, pp. 54-58); John Horgan, "Up in flames," Scientific American (May, pp. 17-24); Christopher Joyce and Dan Charles, 1991, "The battle to stop the Gulf from choking," New Scientist, 23 March, pp. 20-21; Richard D. Small, 199 1, "Environmental impact of fires in Kuwait," Nature, vol. 350, pp. 11-12 (7 March).

John H. Cushman, Jr., 1991, "The environmental toll is mounting in Kuwait as oil-well fires bum on," New York Times, (June 25).

Marlise Simons, 1991, "British study disputes lengthy climatic role for Kuwait oil fires," New York Times (April 16).

John Horgan, 199 1, "Burning questions," Scientific American, July, pp. 17-22.

Matthew L. Wald, 1991, "No global threat seen from Kuwait Oil Fires," New York Times (June 25).

Anthony Lewis, 1991, "What we have wrought, " New York Times (March 29) *

Steven Greenhouse, 199 1, "Rebuilding troubled regions will strain world finances." New York Times (March 26); Patrick E. Tyler, 1991, "U.S. official believe Iraq will take years to rebuild," New York Times (June 3); Alan Cowell, 1991, "Malnutrition ravages children of an Iraqi city," New York Times (June 1).

Newsweek, 1991, "Arms for sale" (April 8, pp. 22-29).

Paul R. Ehrlich and Anne H. Ehrlich, 1991, Healing the Planet, Addison-Wesley, New York.

Bernard Nietschmann, E.W. Pfeiffer, and Vo Quy, 1990, "The ecology of war and peace, (a collection of short articles on the environmental costs of recent wars from Vietnam to Nicaragua)", Natural History, November, pp. 34-49.

Joyce R. Starr, 1991, "Water wars," Foreign Policy No. 82 (spring), pp. 17-36.

For a clear description of this view, see Peter H. Gleick, 199 1, "Environment and security: the clear connections," Bulletin of the Atomic Scientists (April, pp. 17-21).

United Nations Fund for Population Activities (UNFPA), 1991, The State of World Population 1991, UNFPA, New York.

John P. Holdren, 1990, "Energy in transition," Scientific American, 263:3 (September, pp. 156-163).

Paul R. Ehrlich and Anne H. Ehrlich, 1990, The Population Explosion, Simon & Schuster, New York.

Anne H. Ehrlich, 1988, "Development and agriculture" (pp. 75- 100), and David Pimentel, "Industrialized agriculture and natural resources" (pp. 53-74), in P.R. Ehrlich and J.P. Holdren (eds.), The Cassandra Conference, Texas A & M University Press, College Station.

William K. Stevens, 1991, "Loss of genetic diversity imperils crop advances," New York Times (June 25); Robert E. Rhoades, 1991, "The world's food supply at risk," National Geographic, 179:4 (April, pp. 74-105).

Lester R. Brown, et al., 1990, State of the World 1990, W.W. Norton, New York.

Sandra Postel, 1990, "Saving water for agriculture," pp. 39-58, in L.R. Brown, et al.

E.O. Wilson (ed.), 1988, Biodiversity, National Academy Press, Washington, D.C.

Ehrlich and Ehrlich, 199 1.

Norman Myers, 1990, "Deforestation Rates in Tropical Forests and Their Climatic Implications," Friends of the Earth, London.

Paul R. Ehrlich and Anne H. Ehrlich, 198 1, Extinction: The Causes and Consequences of the Disappearance of Species, Random House, New York.

G. Kolata, 199 1, "Tree yields a cancer treatment, but ecological costs may be high," New York Times, May 13; T. Egan, 1991, "Carving out a market for Oregon's yew tree," New York Times, May 31, 1991.

Ehrlich and Ehrlich, 198 1.

P.M. Vitousek, P.R. Ehrlich, A.H. Ehrlich, and P.A. Matson, 1986, "Human appropriation of the products of photosynthesis," BioScience, vol. 36, no. 6 (June), pp. 368-373.

UNFPA, 199 1, The State of World Population 199 1.

Richard Benedick, 1991, Ozone Diplomacy: New Directions for Safeguarding the Planet, Harvard University Press, Cambridge, MA.

For good general discussions of these effects, See World Resources Institute (WRI), 1986, World Resources 1986 (Basic Books, New York) and Fred Pearce, 1990, "Whatever happened to acid rain?" New Scientists, 15 September, pp. 57-60.

For a general discussion of the possible impacts and extensive references, see Ehrlich and Ehrlich, 1991, Healing the Planet, or Stephen Schneider, 1989, Global Warming; Entering the Greenhouse Century, Sierra Club Books, San Francisco.

Norman Myers, 1989, Deforestation Rates in Tropical Forests and Their Climatic Implications, Friends of the Earth, London.

Paul R. Ehrlich and Anne H. Ehrlich, 1989, "How the rich can save the poor and themselves," in S. Gupta and R. Pachuri (eds.) Proceedings of the International Conference on Global Warming and Climate Change: Perspectives from Developing Countries, Tata Energy Research Institute, New Delhi (21-23 February, pp. 287-294).

See articles by John Horgan in Scientific American cited earlier.

Anne H. Ehrlich and John Birks (eds), 1990, Hidden Dangers: The Environmental Consequences of' Preparing for War, Sierra Club Books.

Introducing: Anne H. Ehrlich and Paul R. Ehrlich

Dr. Paul Ehrlich is the Bing Professor of Population Studies, Department of Biological Studies, Stanford University. A member of the Stanford faculty since 1959, he is known internationally for his research on ecological and evolutionary interactions of plants and herbivores, and particularly for his pioneering work on human ecology and population. He is the author of more than 500 scientific papers and articles in the popular press, and some 30 books. Dr. Ehrlich has numerous affiliations and honors including Honorary President of Zero Population Growth, and President of the American Institute of Biological Sciences.

Anne H. Ehrlich is a senior research associate in biology and associate director of the Center for Conservation Biology at Stanford, teaching a course in environmental policy for the University's Human Biology Program since 1981. She has written extensively on issues of public concern such as population control, environmental protection, and environmental consequences of nuclear war. She has served on the White House Council on Environmental Quality and on the University of California's Food Task Force. In 1988, she was elected an Honorary Fellow in the California Academy of Sciences, serving on the editorial board of its journal, Pacific Discovery. In 1989, she was selected for The United Nations' Global 500 Roll of Honour for Environmental Achievement.