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Carrying Capacity Definition Essays

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A biological approach to human problems
by Garrett Hardin

Science, like all human institutions, evolves. Earlier in this century Einstein probably spoke for most of the scientists of his day when he identified the inner force that drew him to scientific work: "I believe with Schopenhauer that one of the strongest motives that lead men to art and science is [the desire to] escape from everyday life with its painful crudity and hopeless dreariness, from the fetters of one's own evershifting desires. A finely tempered nature longs to escape from personal life into the world of objective perception and thought" (Einstein 1935).

Then came the Second World War and the Manhattan Project, culminating on 6 August 1945 with the announcement of the bombing of Hiroshima. Almost overnight scientists realized they could no longer escape becoming involved with the "crudities" of the world. In December of the same year, with Einstein's blessing, the Bulletin of the Atomic Scientists was founded to explore the human implications of scientific discoveries. From the day of its founding, this bulletin has, in the best and truest sense, been a controversial journal. Never again would the escapism of a Schopenhauer be quite so attractive to scientists.

Biologists preceded the physicists in discovering the social perils of pursuing science wherever it might lead. By mid-nineteenth century it was obvious that there were overlaps between the territories claimed by biologists and theologians. Peace-lovers tried to establish a demilitarized zone between two tribes, but it didn't work. In 1925 ideological warfare broke out in Dayton, Tennessee. The legal outcome of the Scopes trial was ambiguous, though one philosopher, as late as 1982, maintained that "the evolutionists won a great moral victory" (Ruse 1982). A different conclusion was reached by the biologist and evolutionist, H. J. Muller. Thirty-four years after the trial, this Nobel laureate noted that the subject of evolution was almost entirely missing from high school biology textbooks. He concluded that, practically speaking, biologists had lost the battle in Dayton. On the centenary of the Origin of Species Muller thundered, "One hundred years without Darwinism are enough!" (Muller 1959).

The next quarter of a century showed that Muller was no mere viewer-with-alarm (Nelkin 1977). During this period the "scientific creation" movement was born. Subsequent successes of the creationists were due in equal measure to their political skill and to the relative apathy of professional biologists. Finally biologists became sufficiently disturbed by what was happening to public education to fight creationists in the courts. Judge William R. Overton's detailed and thoughtful judgement against the creationists in Arkansas on 5 January 1982 foretold the end of the creationists' dominance of the public debate (Montagu 1984).

That is history; but history should never be regarded as mere "water under the bridge." As Santayana said: "Those who cannot remember the past are condemned to repeat it" (Santayana 1905). For more than a century, we biologists failed to do our civic duty by bringing home to the general public the human significance of evolution through natural selection. That which we sowed by a century's near total neglect of public education, we richly reaped in the form of widespread anti-intellectualism fostered by Bible-worshipping fundamentalists. Biology abounds in insights that call for a massive restructuring of popular opinions. If the sad history of Darwinism in the agora is not to be repeated again and again, biologists must accept the responsibility of bringing their insights to the public.

Among the more important biological concepts crying out for public explication today is the idea of "carrying capacity." Resistance to exploring its implications arises in part from the same source as resistance to Darwinism, as illustrated by the following quotations, one of which predates of the Origin of Species by more than two decades.

From the beginning of the nineteenth century, evolution (though not natural selection) was "in the air." In 1837 Cardinal Nicholas Wiseman, perhaps the most influential Roman Catholic in England, disposed of human evolution with these words: "It is revolting to think that our noble nature should be nothing more than the perfecting of the ape's maliciousness" (Wiener and Noland 1957). Obviously the ground was well prepared for the rejection of Darwin's ideas long before he wrote his great book. Darwin's acute awareness of the opposition awaiting his theory no doubt accounted for much of his long delay in publishing the Origin.

How vigorously that opposition expressed itself is well shown by the oft-told story of the Huxley-Wilber-force debate (see, interalia, Hardin 1959 and Brent 1981). Less spectacular, but no doubt more typical, was the reaction of the Victorian lady who, on hearing about Darwin's theory, expostulated: "Descended from the apes! My dear, we will hope that is not true. But if it is, let us pray that it may not become generally known!" (Dobzhansky 1955). It is natural that people committed less to truth than to the stability of society should prefer taboo to confrontation (Hardin 1978).

In what follows, I shall use the term man in the generic sense, to apply to any and all members of the human species regardless of sex. When so used, man is equivalent to the Latin homo rather than vir. This usage is old-fashioned but, I think, aesthetically preferable to expository hybrids of person—(as in personholes, an unhappy substitution for manholes).

Even the most casual reading of the Bible shows that man occupies a very special place in the Judeo-Christian view of the world. Simply put, Darwin's great contribution to public thought was the idea that man is an animal. Not one in a thousand of those who reject Darwinism today do so because they have made a close study of the theory (as laid out, for instance, in any of the standard university textbooks on Darwinian evolution). On the contrary, their rejection has its roots in a highly emotional reaction to the thought that human beings are truly animals, answering to principles that govern all animals. Yet this assumption is the foundation of all biological research into the nature of Homo sapiens.

The contrary assumption, as expressed by Cardinal Wiseman and the anonymous Victorian lady, can be called the hypothesis of human exemptionism, or exemptionism for short (Catton and Dunlap, 1978). The exemptionist assumes, without proof, that men (and women) are exempt from important laws that govern the behavior of other animals. Darwinians do not deny that there are some aspects in which human beings are unique among animals—for instance, in being able to argue about evolution! But Darwinians put the burden of proof on those who make any particular claim of the uniqueness of man.

At various times in the past man was said to be the only animal that could use tools, make tools, communicate with others of his kind, or conceptualize. Soon after each uniqueness was postulated some nonhuman exception was found. Desperately seeking something unique about their own species, apologists even looked for less laudable differentia. On various occasions it was claimed that man was the only animal that made war against his own kind, or that lied, or that committed murder or rape. But again, as fast as negative qualities were put forward, animal exemplars were found.

In the end a few unique human abilities were found. (No other animal conjugates verbs or declines nouns.) But the kinship of man and the animals (meaning "other animals") remains a fruitful working hypothesis for biologists. This hypothesis is recommended to scholars of all persuasions as a sovereign remedy against deceptions engendered by exemptionist thinking. In the end we find that man is indeed a remarkable animal. There is no need to hamstring research at the outset by a commitment to exemptionism.


The management of herds, both wild and domesticated, rests on the concept of carrying capacity. A brief account of David R. Klein's classic study of the reindeer on an Alaskan island will serve to illustrate what carrying capacity means (Klein 1968).

In 1944 some two dozen reindeer were released on St. Matthew Island where previously there had been none. Lichens were plentiful and the animals increased at an average rate of 32% per year for the next 19 years, reaching a peak of about 6,000 in the year 1963. During the heavy snows of 1963-64 almost all of the animals died, leaving a wretched herd of 41 females and 1 male, all probably sterile. It was not so much the inclement weather that devastated the herd as it was a deficiency in food resources, a deficiency that had been brought about by overgrazing.

The carrying capacity of a territory is defined as the maximum number of animals that can be supported year after year without damage to the environment. After careful study Klein concluded that 5 reindeer per km2 was the carrying capacity of an unspoiled St. Matthew Island. An animal census taken in 1957 gave 4 animals per km2. A further 32% increase during the ensuing year would have brought the population to 5.3 per km2, a transgression of the carrying capacity. Had the herd been managed (which it was not), the number would have been kept somewhere near the 1957 size, below 5 per km2.

In developing a policy for dealing with carrying capacity transgressions we must answer two questions: (1) How precise a figure is the stated carrying capacity? and (2) What are the consequences of transgressing the carrying capacity?


There is no hope of ever making carrying capacity figures as precise as, say, the figures for chemical valence or the value of the gravitational constant. On St. Matthew Island the growth of reindeer moss is no doubt greater some summers than others. Certainly the availability of lichens is much less in winter when they must be dug out from under the snow. Then too there are secular variations in climate: the exceptionally severe winter of 1963-64 might have been part of a long-term cycle. To these variations must be added unavoidable variations in expert opinion. As a result, any particular figure for carrying capacity has a substantial element of the arbitrary in it. Should we refuse to build policy upon arguable estimates? What would happen if we ignored all estimates of carrying capacity?

The short answer is disaster. Whenever a population grows beyond the carrying capacity, the environment is rapidly degraded; as a result, carrying capacity is reduced in subsequent years. Uncontrolled, the population continues to grow larger (for awhile) as the carrying capacity grows smaller.

The details of transgression-disasters vary from one situation to another, but some of the consequences are extremely common. Overexploited edible plants are replaced by weeds previously rejected by the exploiting herbivores. Soil that has been laid bare is eroded away; this reduces local productivity in subsequent years. Soil turned into silt fills reservoirs and clogs irrigation systems. Loss of the rain-absorbent capability of soils produces faster runoff after rain, and more devastating floods in lower areas. These effects are especially severe when forests on steep slopes are destroyed.

The consequences of systematically exceeding the carrying capacity are serious and, more often than not, irreversible even when the territory is freed of excess animals. Reversibility may be possible on a geological time scale of tens of thousands of years, but on the time scale of human history such long-term reversibility is no cause for complacency. The Tigris-Euphrates valley, ruined by mismanagement two thousand years ago, is still ruined.

If ecologists were ever asked to write a new Decalogue, their First Commandment would be: Thou shalt not transgress the carrying capacity (Hardin 1976).

Because transgression is so serious a matter, the conservative approach is to stay well below the best estimate of carrying capacity. Such a policy may well be viewed by profit-motivated people as a waste of resources, but this complaint has no more legitimacy than complaints against an engineer's conservative estimate of the carrying capacity of a bridge. Even if our concern is mere profit, in the long run the greatest economic gain comes from taking safety factors and carrying capacities seriously. Is it not time to change the meaning of the word conservative to take account of a new variety, the ecological conservative (Hardin 1985a)? The ecoconservative knows that time has no stop. Proflt seekers who focus too sharply on the bottom line of today's ledger book underestimate the consequences of time's arrow. To the ecologist, bottom line conservatives are not true conservatives. (Unfortunately bottom line conservatives now fill most of the positions on the White House staff.)

The ultimate goal of game management is to minimize the aggregate suffering of animals.


When the numbers of an exploiting herd of animals shoot past the carrying capacity of their environment, what should concerned human beings do? The answer is simple: get rid of the excess fast. This is the correct answer regardless of whether we are primarily concerned with the well being of the animals themselves, or with human profits to be derived from exploiting them.

Quite often the simplest and least cruel way to diminish animal numbers is to shoot the excess. This rational solution has been vigorously opposed since its espousal by Aldo Leopold in the 1930s (Flader 1974). In state after state, the public has had to be educated to see the harm that deer do to themselves when their numbers become too great. Game managers have been opposed by amateur but publicity-wise "animal lovers" (who will henceforth be referred to without quotation marks). With the best of intentions, animal lovers force state agencies to adopt remedies that inevitably lead to more animal suffering. The ill-advised measures include the following.

WINTER FEEDING. The carrying capacity of the land is usually lower in winter than in summer. When a population is no longer kept under control by predators, the numbers rise until there are too many animals to survive a normal winter. The shipping of food to the herd following winter storms prevents Nature's harsh but efficacious remedy for overpopulation. When continued for several seasons, winter feeding produces too many animals even for the summer season, and the environment is subjected to year-round degradation.

TRANSPLANTING. Animal lovers, like some economists (Simon 1981), cannot accept the fact that the world has limits. Whenever the media carry accounts of starving deer, someone is sure to propose that the animals be forcibly moved to other areas that, curiously, are assumed to be both suitable and underpopulated. When such experiments are carried out, the results are invariably expensive and unsatisfactory.

ADOPTION. Wild horses (really feral horses) in the western United States tug strongly at the heartstrings of animal lovers. Years of political pressure, orchestrated by "Wild Horse Annie" Johnston, finally compelled Congress to pass the Wild Free-Roaming Horses and Burros Act of 1971. This act forbids private citizens or commercial enterprises to kill, capture, or harass wild equines on federal lands.

Wild horses increase by about ten percent per year, which means a doubling of the population every seven years. Unfortunately, the rate of increase of the grazing lands is a negative number. Something has to give. So the Bureau of Land Management (BLM 1980) set up an "Adopt A-Horse Program" to reduce the herds in an acceptable manner. A US resident, after filling out an application form and paying $200 for a horse or $75 for a burro, can pick up and transport (at his own expense) an animal to take to his home property. If the adopter takes care of it in an approved manner for one year he can then obtain title to it.

The animals are rounded up by combined ground and helicopter crews. The psychic trauma of such a roundup is presumed, without evidence or inquiry, to be less than the trauma of being shot. The cost to the government of each animal adopted, after subtracting the adoption fee collected was $400 in flscal year 1981, and $474 in fiscal year 1982 (BLM 1982). Thus is the expense of unwanted cruelty commonized (Hardin 1985b) .

How many Americans have a suitable horse lot, and the money and the inclination to adopt a wild horse? The number is unknown. How fast is the number of potential adopters increasing? With continued urbanization the population of potential adopters is undoubtedly shrinking. Meanwhile the wild horse population grows at plus ten percent per year.

The working of the mind of the committed animal lover is one of the wonders of nature. Light is thrown on this wonder by a statement made in Florida in 1982, when a portion of the Everglades became seriously overpopulated with deer. The state Game and Fresh Water Commission recommended that the deer population of 5,500 be reduced by killing 2,250 animals (41%). Reacting to this proposal a Florida attorney sought a court injunction to protect the lives of innocent, helpless, harmless, and otherwise happy creatures that have been placed on earth by God to be free from the torment of man." He claimed that killing any of the animals would amount to a "deprivation of the rights of the deer to live freely and peacefully on earth, according to nature's order" (Florida 1983).

In other words, this attorney was extending into the animal realm the idea of the "sanctity of life" that many ethicists accept in the human realm. Ironically, this amounts to a denial of the exemptionism that is usually supported by those who reject the conclusions of biology. Curiously, the manner of the rejection is the exact opposite of that practiced by biologists: animals lovers would endow animals with the gifts usually reserved for human beings.

Animal lovers and professional biologists should be able to agree on the ultimate goal of game management: to minimize the aggregate suffering of animals. They differ in their time horizons and in the focus of their immediate attention. Biologists insist that time has no stop and that we should seek to maximize the wellbeing of the herd over an indefinite period of time. To do that we must "read the landscape," looking for signs of overexploitation of the environment by a population that has grown beyond the carrying capacity.

By contrast, the typical animal lover ignores the landscape while focusing on individual animals. To assert preemptive animal rights amounts to asserting the sanctity of animal life, meaning each and every individual life. Were an ecologist to use a similar rhetoric he would speak of the "sanctity of carrying capacity." By this he would mean that we must consider the needs not only of the animals in front of us today but also of unborn descendants reaching into the indefinite future.

Time has no stop, the world is finite, biological reproduction is necessarily exponential: for these combined reasons the sanctity strategy as pursued by animal lovers in the long run saves fewer lives, and these at a more miserable level of existence, than does the capacity strategy pursued by ecologically knowledge able biologists.

Thus do we have the paradox that the interests of an animal species are best served by focusing attention on the environment rather than the individual animals. The environment is taken as a "given," and the animal population is made to match the capacity of the environment.


So far as it is within our power we surely would like to manage human populations under the ideal used for animals, namely, to minimize suffering and maximize happiness over many generations. This means that, for human populations as for others, the prime commandment must be Thou shalt not transgress the carrying capacity.

Most of the principles worked out for populations of nonhuman animals apply with little change to human populations. Carrying capacity must take account of seasonal variations—hence Aesop's story "The Ant and the Grasshopper." Long cycle secular variations may also be important (though man, the inveterate optimist, seldom takes really adequate account of future threats). And variations in expert opinion are even greater when we deal with the human situation.

For nonhuman animals it seems reasonable to measure carrying capacity in terms of resources available for survival. In evaluating the human situation, however, we are not satisfied with so simple a metric. We hold that "Man does not live by bread alone." We go beyond the spiritual meaning of the Biblical quotation in distinguishing between mere existence and the good life. This distinction, like so many population-related ideas, was well understood by Malthus, who held that the density of population should be such that people could enjoy meat and a glass of wine with their dinners. Implicitly, Malthus's concept of carrying capacity included cultural factors.

The good life, then, must include a reasonable (though undefined) amount of luxury food (fresh vegetables, quality meats, delicious drinks), clothing beyond that needed for mere conservation of body heat, comfortable housing, adequate transportation, space heating and cooling, electronic entertainment, vacations, etc., etc.

There is no agreed upon metric to which we can reduce the various goods so that we can compare the level of living of one people with another. There is, however, a useful partial measure. and that is the units of energy used per capita year in the various countries.

Periodically the United Nations publishes a measure of energy use, stated in terms of kilograms of coal equivalent per capita per annum. Consider the following figures for the year 1982: Ethiopia, 31; World, 1,823; United States, 9,431 (UN 1984). On a relative basis, setting Ethiopia equal to unity, these become: Ethiopia, 1; World, 59; United States, 304.

Admittedly, many real components of the quality of life are left out of this energy measure, e.g., many aesthetic goods, interpersonal goods, and perhaps even spiritual goods. Material energy sources are, to a large extent, interconvertible as sources of material goods and facilitators of immaterial goods. Wood can be burned to cook food, burned to heat a house, or used to construct a house. Oil can cook food, heat a house, or be used to create raw materials for an artistic painting. Crude as it is, the measure of people's energy consumption at least yields a first approximation to the material quality of their life.

The enjoyment of nonmaterial goods requires at least a minimum of material well-being. On this crude measure, the average inhabitant of the world is about 60 times as well off as an average Ethiopian, while Americans are more than 300 times as well off. Anyone who goes to Ethiopia and tries to live the life of an average Ethiopian will conclude that these flgures cannot be far wrong.

Carrying capacity is inversely related to the quality of life. When dealing with human beings there is no unique figure for carrying capacity. So when a pronatalist asserts (Revelle 1974) that the world can easily support 40 to 50 billion people—some ten times the present population -- he need not be contradicted. If everyone lived on the energy budget of the Ethiopians, the earth might support 60 times the present population, or about 300 billion people.

The figure just given is only a crude estimate. In less hospitable regions, e.g., in Lappland, energy must be used to produce more clothing or space heating. In the Imperial Valley of California, energy must be used for the importation and pumping of water. But such facts are no more than the details that would be needed to refine the estimate of the maximum possible population supportable by the earth—if such an estimate is worth refining, which is doubtful.

In the physical sciences the most basic terms stand for entities that are "conserved under transformations," that is for entities that remain quantitatively the same when qualitatively changed. Mass and energy are such conservative concepts. Without conservative concepts intellectual anarchy takes over and analysis becomes impossible.

In bioeconomics carrying capacity plays a conservative role. In the nonhuman world its application presents few problems. Carrying capacity does not vary without cause; it does not increase in response to need; it cannot be transgressed with impunity; and its definition in particular circumstances presents no serious problem to the well-informed. Such is the situation so long as we deal only with nonhuman populations.

When we move to human populations, however, the situation changes. The naive question, "What is the human carrying capacity of the earth?" evokes a reply that is of no human use. No thoughtful person is willing to assume that mere animal survival is acceptable when the animal is Homo sapiens. We want to know what the environment will carry in the way of cultural amenities, where the word culture is taken in the anthropological sense to include all of the artifacts of human existence: institutions, buildings, customs, inventions, knowledge. Energy consumption is a crude measure of the involvement of culture. It may not be the best measure possible, but it will do for a first approach.

When dealing with human problems, I propose that we abandon the term carrying capacity in favor of cultural carrying capacity or, more briefly cultural capacity. As defined, the cultural capacity of a territory will always be less than its carrying capacity (in the simple animal sense). Cultural capacity is inversely related to the (material) quality of life presumed. Arguments about the proper cultural capacity revolve around our expectations for the quality of life. Given fixed resources and well-defined values, cultural capacity, like its parent carrying capacity, is a conservative concept.


Suppose resources are not fixed? If by resources we mean natural resources that are available for human use at a particular time, at a particular stage in technological development, then resources have not been firmly fixed during all of human history. The past two centuries have seen the most spectacular increase in the resources actually available for human use. Malthus, because he was not acutely aware of the increase in carrying capacity going on in his time, was so unlucky as to put forth a theory of population that was too static to suit the economists of subsequent times, who are keenly aware of the effect of technology on the resources effectively available to the human species.

A careful reading of Malthus's work shows that he described what we would now call a cybernetic system in which negative (or corrective) feedbacks keep the population fluctuating about a relatively fixed set point (Hardin and Bajema 1978). The set point is, of course, the carrying capacity of the environment. Unfortunately for Malthus's reputation, the spectacular development of technology in the years after 1798 moved the set point steadily upward.

Biologists find no difficulty in fitting this new fact into the Malthusian cybernetic scheme, but many economists and other social scientists see the continued increase in available resources as incompatible with Malthusian theory. The difference in opinion is closely connected with a difference in the perception of time (Hardin 1985b). Economics, the handmaiden of business, is daily concerned with "discounting the future," a mathematical operation that, under high rates of interest, has the effect of making the future beyond a very few years essentially disappear from rational calculation. Told that petroleum resources will, for all practical purposes, be exhausted in 20 years, the biologist starts to worry, while the economist merely yawns. For most economic planning, the ultimate horizon of time is only five years away.

The economist can give two rather telling arguments for continuing to refuse to take seriously any predictions of the state of the world more than five years from now. First, for more than two centuries science has come up with one miracle after another, steadily increasing the functional carrying capacity of the world.


Scientists see less of the miraculous in the development of technology. I am afraid that many economists see "Science-and-Technology" as a magician with a bottomless hat out of which an endless series of rabbits can be pulled. Economists have difficulty taking energy shortages seriously. They say: "First we had wood for fuel. As that became exhausted, we found we could use coal. Before that became exhausted, we discovered oil. As we began to worry about the supply of that, we discovered atomic energy. It looks like atomic energy is inexhaustible; but if it isn't, why worry? Scientists will discover something else; and just in time, as they always have in the past." Such faith may be heartwarming, but it is also dangerous.

Economists have advanced another excuse for never worrying (Simon 1981), which is rather subtle and more difficult to deal with. Quoting Aesop, they maintain that "Necessity is the mother of invention." This is certainly at least a half-truth. But some economists go on to imply that the greater the necessity, the greater the inventiveness. This may be seriously doubted. In our time, necessity is greatest in wretchedly poor countries like Bangladesh and Ethiopia; but is inventiveness at its maximum in such poor countries? Certainly not.

The stimulus of necessity is most effective when the standard of living includes a considerable surplus of resources (luxury) available for investment in the chancey activities of investigation, invention, and testing.

Put another way, when the scale of living falls so far below the cultural carrying capacity as to preclude effective inventiveness—when the cultural capacity is seriously transgressed—then living conditions spiral downward as the good life degenerates into mere existence sans inventiveness. Translated into human terms, the ecological first commandment becomes: Thou shalt not transgress the cultural capacity.


To whom is the first commandment of ecology addressed: to the whole world acting as a unit, or to subdivisions of the world? Is it wise to hope and plan for One World, a world without borders? Or must our plans assume the continuation of subdivisions something like the nations we now know? This is perhaps the most fundamental political question of our time. The insights of biology are needed to solve it.

The dream of One World has ancient roots. Buddha, born more than half a millennium before Christ, took a universalist position. He seems to have had little direct influence on the development of Western thought. Diogenes, in the fourth century BC, rejected mere patriotism, calling himself kosmopolites, a citizen of the world. Zeno of Citium, in the next century, committed Stoicism to the same ideal. Christianity apparently derived this universal ideal from the Stoics. Though parishes developed as a valuable administrative unit of the church, the guiding ideal of Christianity has departed more and more from parochialism (L. parochia, diocese or parish).

During the past century the production of literature extolling One World has been a "growth industry." For this there are two reasons, one good and one bad (or at any rate, insufficient). The good reason has its roots in the consequences of the growth of population and technology. Population growth shrinks the regions between competing sovereignties and brings us every day closer to "living in each other's pockets." Technology, ever more puissant in both war and peace, exacerbates the consequences of propinquity. The mounting dangers of such commonized disasters as acid rain, the greenhouse effect, and the nuclear winter make anybody's business everybody's business. A purely localized solution to such problems is no solution at all. When it comes to the commons of water and air, we truly live in One World, whether or not we are clever enough to make the appropriate political adjustments.

The insufficient reason for the decline of parochialism in our time arises from a philosophical error. Wealth comes in only three forms: matter, energy, and information. The first two forms obey conservation laws: their exchanges are of the zero-sum sort. What Peter gains, Paul loses. When it comes to material wealth, selective forces operate against generosity and in favor of self-interest.

By contrast, exchanges of information are not bound by conservation principles: positive-sum outcomes are possible. The information that Peter gives to Paul does not make Peter the poorer. Moreover, Paul may operate on that information, later handing it back to Peter in improved form. That's a plus-sum relationship. Within limits, selection favors cautious generosity and disfavors extreme selfishness when it comes to the wealth of information. Other things equal, when it comes to the distribution of information, a world without borders should be a richer world than one divided into tight-lipped parishes.

Nowhere has the rejection of parochialism been stronger than in the world of science and scholarship generally. Those who deal primarily with ideas may quite unconsciously generalize the plus-sum property of information exchanges into the domains of matter and energy, where it does not apply. It is not uncommon for dealers in information to naively suppose that Karl Marx's "From each according to his ability, to each according to his needs" (Marx 1972) is a wise rule to follow in exchanges involving matter and energy (as well as information).

I believe I have shown in "The Tragedy of the Commons" (Hardin 1968) that the promiscuous sharing of matter and energy leads to universal ruin. The argument may be restated in new and more biological terms. If discrete entities (nations, for example) are in reality competing for scarce resources, those entities that follow Marx's ideal will be at a competitive disadvantage competing with more self-seeking entities. The selective value of Marx's ideal is negative, so long as the number of administrative entities is greater than one.

But what if there is only one administrative unit? What if we succeed in creating the One World yearned for by Christians, Marxists, and countless other groups? Never mind that many keen minds have regarded this possibility as being highly improbable. What if...?

Bertrand Russell has given the answer. To survive as a cohesive unit, an entity must be held together by some sort of cohesive force. Says Russell: "Always when we pass beyond the limits of the family it is the external enemy which supplies the cohesive force....A world state, if it were firmly established, would have no enemies to fear, and would therefore be in danger of breaking down through lack of cohesive force" (Russell 1949). The writers of science fiction have long been aware of this, repeatedly creating a scenario that brings the nations of the world into a genuine union through the threat of enemies from outer space. Unfortunately, all experience with space, to date, has given us no hope of discovering such enemies. So the problem One World or Many? remains with us.

I have argued elsewhere (Hardin 1982) that no single way will suffice to administer the affairs of what some people call "Spaceship Earth." There must be some sort of fragmentation of administrative tasks, though a universal approach is needed for the protection of the commons of air and water. But most material wealth is, after all, fragmented around the world; parochial distribution calls for parochial controls. This logical necessity meshes well with the territorial instincts that have been selected for during millions of years of biological evolution. How the necessary "mixed economy" of administration is to be created and sustained is an enormous problem.

In the meantime, whether or not we discover how to administer the commons of air and water, we must clarify our thoughts about the impact of competitive living on cultural carrying capacities. As before, let us allow per capita energy use to deputize for the total standard of living. This is an oversimplification of the real world, but the consequences deduced are general and would hold up under a more thorough analysis.

In making comparisons of one group of people with another it is difficult to attain objectivity, because we are one of the world's groups and we have varying relations with all the others. It will help, I think, if we use the intellectual device of the "man from Mars," the observer who can be perfectly objective about earthly affairs because he has no terrestrial ties.

The man from Mars makes a tour of the earth and notes the widely varying standards of living and the widely varying densities of population. He also notes that resources vary widely in their distribution. Having evolved by natural selection on Mars—is there any other way to evolve?—our martian (like earthlings) has strong territorial feelings. He points out that a parochial distribution of resources should be matched by parochial consumption. This general principle does not preclude international trade when a particular resource is in very short supply in a particular nation; by trading parts of their relative surpluses, trading nations can mutually gain.

The per capita consumption of energy in Bangladesh is one thirty-eighth as great as the world average. Spokesmen for the country complain about this low energy income. (The material quality of life, however measured, seems correspondingly low.) How should others react to this discrepancy?

The standard earthly response is to say, "Bangladesh suffers from shortages." Thus do earthlings demonstrate their fellow-feeling for the Bangladeshi, even though this may be the only way they do so. But what would the man from Mars say? Being under no felt necessity to demonstrate fellow-feeling, he might well respond thus: "Shortage, you say? Shortage of resources? If parochial resources are being fully used, how can there be a shortage? Parochial demand should match parochial supply. Why not say there is a longage in demand? Though it may not be possible to increase supply, it is always possible to decrease demand. You do this either by reducing people's expectations, or by reducing the number of people who have expectations—which can always be done by reducing the birth rate. (There is no necessity to increase the death rate.)"

Continuing, the man from Mars says: "If each Bangladeshi enjoys only one thirty-eighth as much energy as the average earthling, maybe there are 38 times too many people living in Bangladesh? Should we not speak of a 'longage' of people, rather than a shortage of resources? In principle, a longage is always soluble; a shortage may not be."

If Bangladesh reduced its present population of 104 million people by a factor of 38 it would have only 2.7 million people. It is of interest to note that the state of Iowa has exactly the same area as Bangladesh, but with only 2.9 million people. There are many significant differences between the two areas, so not too much should be made of the contrast in population. But the equivalence does show that the suggested population for Bangladesh is not terribly unreasonable.

Adopting the martian principle that parochial demands should match parochial supplies would eliminate one important excuse for aggressive international actions. Implicitly thinking in One World terms easily leads to the concept of poor or "have-not" nations. An excessive passion for justice can then easily lead to the assertion that being poor justifies corrective military action. In our thermonuclear world, is there any justice that would justify embarking on an uncontrollable war?

By contrast, the carrying capacity approach results in replacing the concept of a "have-not" nation with that of an "overpopulation" nation. It's a rare piece of property that cannot support a suitably small population in comfort. This does not mean that every territory will have a helping of all the amenities of life: people who live in Spitzbergen should not assert their right to tropical beaches, nor people in Bali their right to skiing. The exceptional property that cannot meet a minimum standard for human existence should have a zero population. It makes no sense to say that every territory has a right to be occupied by a human population. Some wretched territories now inhabited should be abandoned.

Overpopulation can be corrected by means short of homicide and war. The means is attrition, which means seeing to it that the birth rate falls below the death rate (Hardin 1985b). This may be painful, but it is not war. For members of the Western world, part of the pain of adjustment of population to reality arises from the necessity of reexamining and substantially modifying our concept of human rights. In this reexamination, the deep concept of cultural carrying capacity must play a central role.

Garrett Hardin, professor emeritus of human ecology at the University of California, Santa Barbara, received the 1986 AIBS Distinguished Service Award for his contributions in the field of ecology and his long-time efforts to apply scientific methods to the ethical and political dilemmas posed by population growth and resource depletion. This is the text of his acceptance speech, given 10 August 1986 at the AIBS Annual Meeting at the University of Massachusetts, Amherst.

References cited

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Dobzhansky, T. 1955. Evolution. Genetics and Man. John Wiley & Sons, New York.

Einstein, A. 1935. The World As I See It. John Lane and Bodley Head, London.

Flader, S.L. 1974. Thinking Like a Mountain. University of Missouri Press, Columbia.

Florida, State of. 1983. Everglades Emergency Deer Hunt Controversy. Florida Game and Fresh Water Fish Commission, Tallahassee.

Hardin, G. 1959. Nature and Man's Fate. Holt, Rinehart & Winston, New York.

1968. The tragedy of the commons. Science 162: 1243-1248.

1976. Carrying capacity as an ethical concept. Soundings 59: 120- 137.

1978. Stalking the Wild Taboo, 2nd ed. W.H. Freeman, San Francisco.

1982. Discriminating altruisms. Zygon 17: 163- 186.

1985a. Human ecology: the subversive, conservative science. Am. Zool. 25:469-476.

1985b. Filters Against Folly: How to Survive Despite Economists. Ecologists, and the Merely Eloquent. Viking Penguin, New York.

Hardin, G., and C. Bajema. 1978. Biology: Its Principles and Implications. 3rd ed. W.H. Freeman, San Francisco.

Klein, D.R.1968. The introduction, increase, and crash of reindeer on St. Matthew Island. J. Wildl. Manage. 32: 350-367.

Marx, K. 1972. Critique of the Gotha program. Pages 382-398 in R. C . Tucker, ed. The Marx Engels Reader. W.W. Norton, New York.

Montagu, A., ed. 1984. Science and Creationism. Oxford University Press, New York.

Muller, H.J. 1959. One hundred years without Darwinism are enough. School Sci. Math. 59: 304.

Nelkin, D. 1977. Science Textbook Controversies and Politics of Equal Time. MIT Press, Cambridge, MA.

Revelle, R. 1974. Food and population. Sci. Am. 231: 161-170.

Ruse, M. 1982. Darwinism Defended: A Guide to the Evolution Controversies. Addison-Wesley Publ. Co., Reading, MA.

Russell, B. 1949. Authority and the Individual. Unwin Books, London.

Santayana, G. 1905. Flux and constancy in human nature. Page 284 in The Life of Reason, 2nd ed. Scribner's, New York.

Simon, J .1981. The Ultimate Resource. Princeton University Press, Princeton, NJ.

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Wiener, P.P., and A. Noland, eds. 1957. Roots of Scientific Thought. Basic Books, New York.

Carrying Capacity Network . FOCUS/Volume 2, No. 3, 1992

Carrying Capacity Network 1325 G Street, NW Suite 1003 Washington, DC 20005 Phone: 800-466-4866 or 202-879-3044 FAX: 202-296-4609 E-MAIL CCN@IGC.APC.ORG

by Albert A. Bartlett, Department of Physics, University of Colorado



The related terms, “sustainable” and “sustainability” have become popular and are used to describe a wide variety of activities which are generally ecologically laudable. At the same time, the term “compromise” is heard more frequently because the needs of the environment often are in conflict with the needs of humans. A brief examination of the question of compromise shows that a series of ten compromises, each of which saves 70% of the remaining environment, results in the saving of only 3% of the environment. Judging from the ways in which the terms “sustainable” and “sustainability” are used, their definitions are not very precise, especially when compromises are involved. An attempt is made here to give firm definition to these terms and to translate the definition into a series of laws and hypotheses which, it is hoped, will clarify the implications of their use. These are followed by a series of observations and predictions that relate to “sustainability.”


In the 1980s it became apparent to thoughtful individuals that populations, poverty, environmental degradation, and resource shortages were increasing at a rate that could not long be continued. Perhaps most prominent among the publications that identified these problems in hard quantitative terms and then provided extrapolations into the future as well as recommendations for corrective actions, was the book Limits to Growth (Meadows, et.al., 1972) which simultaneously evoked admiration and consternation. The consternation came from traditional “Growth is Good” groups all over the world. Their rush to rebuttal was immediate and urgent, prompted perhaps by the thought that the message of Limits was too terrible to be true. (Cole, et.al, 1973) As the message of Limits faded, the concept of limits became an increasing reality with which people had to deal. Perhaps, as an attempt to offset or deflect the message of Limits, the word “sustainable” began to appear as an adjective that modified common terms. It was drawn from the concept of “sustained yield” which had been used to describe agriculture and forestry when these enterprises were conducted in such a way that they could be continued indefinitely, i.e., they could be sustained. The use of the term “sustainable” provided comfort and reassurance to those who may momentarily have wondered if possibly there were limits. So the word was soon applied in many areas, and with less precise meaning, so that for example, “development” became “sustainable development,” etc. One would see political leaders using the term “sustainable” to describe their goals as they worked hard to create more jobs, to increase population, and to increase rates of consumption of energy and resources. These terms seem to have been redefined flexibly to suit a variety of objectives and conveniences.

A sincere concern for the future is certainly the factor that motivates many who make frequent use of the word, “sustainable.” But there are cases where one suspects that the word is used carelessly, perhaps as though the belief existed that the use of the adjective “sustainable” is all that is needed to create a sustainable society.

“Sustainability” has become big-time. University centers and professional organizations have sprung up using the word “Sustainable” as a prominent part of their names. In some cases, these may be illustrative of what might be called the “Willie Sutton school of research management.” (Sutton) For example, a governor recently appointed a state advisory committee on global warming. The charge to the committee was not to see what the state could do to reduce its contribution to global warming, but rather the committee was to work to attract to the state, companies and research grants dealing with the topic of global warming.

For many years, studies had been conducted on ways of improving the efficiency with which energy is used in our society. These studies have been given new luster by referring to them now as studies in the “sustainable use of energy.”

In the extreme case, one reads about “sustainable growth.”

“…the discussions have centered around the factors that will determine [a] level of sustainable growth of agricultural production.” (Abelson, 1990)

If we accept the idea that “sustainable” means for long indefinite periods of time, then we can see that “sustainable growth” implies “increasing endlessly,” which means that the growing quantity will tend to become infinite in size. The finite size of resources, ecosystems, the environment, and the Earth lead one to recognize that the term “sustainable growth” is an oxymoron. Yet the term is used by our leaders. In a recent report from the Environmental Protection Agency we read that

President Clinton and Vice President Gore wrote in Putting People First, “We will renew America’s commitment to leave our children a better nation – – a nation whose air, water, and land are unspoiled, whose natural beauty is undimmed, and whose leadership for sustainable global growth is unsurpassed.” (EPA, 1993)

And so we have a spectrum of uses of the term “sustainable.” At one end of the spectrum, the term is used with precision by people who are introducing new concepts as a consequence of thinking profoundly about the long-term future of the human race. In the middle of the spectrum, the term is simply added as a modifier to the names and titles of very beneficial studies in efficiency, etc. that have been in progress for years. Near the other end of the spectrum, the term is used as a placebo. In some cases the term may be used mindlessly (or possibly with the intent to deceive) in order to try to shed a favorable light on continuing activities that may or may not be capable of continuing for long periods of time. At the very far end of the spectrum, we see the term used in a way that is internally contradictory.

This wide spectrum of meanings is a source of confusion because people can ask, “Just exactly what is meant when the word ‘sustainable’ is used?” Is the use of the word “sustainable” sufficient to identify the user as one who is widely literate, numerate, and ecolate, in matters relating to the long-range problems of the human race?

Let us examine the use of the term “sustainable” in one of the major global reports to see if we can gain a better idea of the intended meaning of the word.


The terms “sustainable” and “sustainability” burst into the global lexicon in the 1980s as the electronic news media made people increasingly aware of the growing global problems of overpopulation, drought, famine, and environmental degradation that had been the subject of Limits to Growth in the early 1970s, (Meadows, et.al., 1972). A great burst of increased awareness came with the publication of the report of the United Nations World Commission on Environment and Development, the Bruntland Report, which is available in bookstores under the title Our Common Future. (Bruntland, 1987)

In graphic and heart-wrenching detail, this Report places before the reader the enormous problems and suffering that are being experienced with growing intensity every day throughout the underdeveloped world. In the foreword, before there was any definition of “sustainable,” there was the ringing call,

What is needed now is a new era of economic growth – growth that is forceful and at the same time socially and environmentally sustainable. (p.xii)

One should be struck by the fact that here is a call for “economic growth” that is “sustainable”. What is “economic growth?” Is it an increase in economic activity per capita, or is it an increase in total economic activity? Whatever the definition, one has to ask if it is possible to have an increase in ecomomic activity without having increases in the rates of consumption of non-renewable resources? If so, under what conditions can this happen? Are we moving toward those conditions today? As we have seen, these two concepts of “growth” and “sustainability” tend to conflict with one another, yet here we see the call for both. The use of the word “forceful” would seem to imply “rapid,” but if this is the intended meaning, it would just heighten the conflict. A few pages later in the Report we read,

Thus sustainable development can only be pursued if population size and growth are in harmony with the changing productive potential of the ecosystem.(p.9)

One begins to feel uneasy. What does the Commission mean by the phrase “in harmony with…?” It can mean anything. By page 11 the Commission acknowledges that population growth is a serious problem, but then

The issue is not just numbers of people, but how those numbers relate to available resources. Urgent steps are needed to limit extreme rates of population growth.

The suggestion that “The issue is not just numbers of people” is alarming. Neither “limit” nor “extreme” are defined, and so the sentence gives the impression that most population growth is acceptable and that only the “extreme rates of population growth” (“extreme” is not defined) need to be dealt with by some undefined process of limiting. By page 15 we read that

A safe, environmentally sound, and economically viable energy pathway that will sustain human progress into the distant future is clearly imperative.

Here we see the recognition that energy is a major long-term problem and we see the important acknowledgment that “sustainable” means “into the distant future.”

As the authors of the Report searched for solutions, they called for large efforts to support “sustainable development.” The most commonly quoted definition of “sustainable development” appears in the first sentence of Chapter 2,(p.43)

Sustainable development is development that meets the needs of the present without compromisingthe ability of future generations to meet their own needs.

This definition, coupled with the earlier statement of the need to “sustain human progress into the distant future,” should form the basis for our understanding of the use of the term, “sustainable development.”

Unfortunately, the definition gives no hint regarding the courses of action that could be followed to meet the needs of the present, but which would not limit the ability of generations, throughout the distant future, to meet their own needs.

The Commission’s recognizes that there is a conflict between population growth and development:(p.44)

An expansion in numbers [of people] can increase the pressure on resources and slow the rise in living standards in areas where deprivation is widespread. Though the issue is not merely one of population size, but of the distribution of resources, sustainable development can only be pursued if demographic developments are in harmony with the changing productive potential of the ecosystem.

Can the Commission mean that population growth slows the rise of living standards only “in areas where deprivation is widespread?” This statement again plays down the role of population size in exacerbating resource and environmental problems. The Commission repeats the denial that the problems relate to population size and it shifts the blame to the distribution of resources. The Commission then speaks of “demographic developments,” whatever that may mean, which must
be “in harmony with…”, whatever that means. If one accepts reports that the “global productive potential of ecosystems” is declining, due to deforestation, the loss of topsoil, pollution, etc., then the “in harmony with…” could mean that population also will have to decline. But the Commission is very careful not to say this.

These quotations (above) are thought to be representative of the vague and sometimes contradictory messages that are in this important report.

It seems that the Bruntland Commission Report’s definition of “sustainability” was, with reason, both optimistic and vague. The Commission probably felt that the definition had to be optimistic, but given the facts, it was necessary to be vague in order not to appear to be pessimistic. Straight talk about the meaning of “sustainability” is similarly avoided in a more recent report that came out of the 1992 Earth Summit in Rio de Janerio, which was

…the largest gathering of world leaders in history [which] endorsed the principle of sustainable development. (Committee for a National Institute for the Environment, 1993)

The report carries the impressive title, Agenda 21, The Earth Summit Strategy to Save Our Planet (Sitarz, 1993) The text discusses the relation between population growth and the health of the planet.

The spiraling growth of world population fuels the growth of global production and consumption.
Rapidly increasing demands for natural resources, employment, education and social services make
any attempts to protect natural resources and improve living standards very difficult. There is an
immediate need to develop strategies aimed at controlling world population growth.(p.44)

The first sentence is quite reasonable, but in the third sentence, what is meant by “controlling?” The dictionary suggests meanings such as, “To check or regulate; to keep within limits; to exercise directing, guiding or restraining power over..” “Controlling world population growth” could mean, “hold the annual population growth rate at its present value of approximately 1.7%,” which surely was not their intent. Why do they use the phrase “controlling world population growth” when one suspects that they know full well that the critical challenge is to “stop world population growth?” Having thus made a politically correct statement of the problem, the Report then lists, under the heading, “Programs and Activities”, the things that need to be done. Here we would expect that the authors would concentrate on the hard realities. Instead, it is all whipped cream. Perhaps their
strongest recommendation is

The results of all research into the impact of population growth on the Earth must be disseminated as widely as possible. Public awareness of this issue must be increased through distribution of population-related information in the media.(p.45)

How are we going to increase public awareness of the problem of population growth if the crucial report that purports to give guidelines for the future won’t talk frankly and honestly about the problem? How are we going to educate the public about the problem of population growth if we fail ourselves to give concrete details of “the impact of population growth on the Earth?”

Then, under the next heading of “National Population Policies” we read that

The long term consequences of human population growth must be fully grasped by all nations. They must rapidly formulate and implement appropriate programs to cope with the inevitable increase in population numbers. (p.45)

The authors indicate here that they know that there are serious “long term consequences of human population growth.” These consequences could have been explored in simple, concrete, and illuminating detail, and yet the authors fail to do the exploring. The authors could have educated us about the “long-term consequences of continued population growth” and then could have
identified for us the appropriate remedial courses of action which are necessary to achieve zero growth of population as rapidly as possible. By referring to the “inevitable increase in population numbers” the authors seem to say that there is nothing that can be done.

This book is loaded with admonitions suggesting that we all go out and embark on programs that are sustainable. In enumerating the things that the authors feel have to be done, the report has both the comprehensive scope and the literary style of the Yellow Pages. The book makes many references to sustainability, yet it artfully dodges the central issues relating to the meaning of “sustainability.”

Distribution, harmony, and “improvement in the capacity to assess the implications of population patterns” are important, but it seems clear that improvements in the human condition cannot be achieved without understanding and recognizing the importance of numbers, and in particular, numbers of people. As we look here in the United States, and around the world, we can see that the numbers of people are growing, and we can see places where the problems associated with the growth are so overwhelming as to make it practically impossible to address the vitally important issues of distribution, equity, and harmony.

The failure of writers to address the population problem was underscored recently by Robert M. May (May, 1993). May, who is Royal Society Research Professor at the University of Oxford and Imperial College, London, was reviewing a new book on biological diversity. He observes that the book says relatively little about the continuing growth of human populations. But this is the engine that drives everything. Patterns of accelerating resource use, and their variation among regions, are important but secondary: problems of wasteful consumption can be solved if population growth is halted, but such solutions are essentially irrelevant if populations continue to proliferate. Every day the planet sees a net increase (births less deaths) of about one quarter of a million people. Such numbers defy intuitive appreciation. Yet many religious leaders seem to welcome these trends, seemingly motivated by calculations about their market share. And governments, most notably that of the U.S., keep the issue off the international agenda; witness the Earth Summit meeting in Rio de Janerio. Until this changes, I see little hope.


Environmental conflicts are often portrayed in ways that pit the needs of humans against the needs of the environment, perhaps in the belief that most people feel that the environment is unlimited, and therefore how it is treated is irrelevant. This leads to calls for compromise. Humans will take a little of the environment, and some of the environment will be temporarily left untouched. It is urgent that we be aware that these compromises reduce the rate of destruction of the environment (which is good), but in most instances, the ultimate result of a succession of many compromises is the destruction of the environment. For example, instead of losing 60% of the local environment in some proposed development, a compromise might result in loss of only 30% of the environment, while 70% is saved. This is good; but one needs to know that a series of ten such compromises, each of which saves 70% of the remaining environment, will result in the loss of all but about 3% of the environment. (0.710 = 0.03) There have been situations where compromises have resulted in the preservation of large reserves in order to allow other critical areas to be set aside for human settlement and agriculture. It will be interesting to see how these compromises hold up in the face of the pressures of growing populations.

Preserving the environment can lead to frustrations. In contrast to the active promotion of population growth that is seen in most communities, a community can go to great effort and expense to purchase and to preserve open space for the benefit of generations yet to come. The result is predictable. People, industries, and businesses want to move to the communities that have preserved open space and have other environmentally sensitive programs and policies. Thus the effort to preserve a local environment helps to destroy the preservation that has been achieved.

Jerome B. Wiesner was President of M.I.T. (1971-1980) and was Special Assistant for Science and Technology for Presidents Kennedy and Johnson. He made a very sobering observation about the conflict between the needs of humans and the needs of the environment. (Wiesner, 1989)

There are no clear-cut ways to reconcile economic growth with the measures needed to curb
environmental degradation, stretch dwindling natural resources and solve health and economic


The term “carrying capacity,” long known to ecologists, has also recently become popular. It “refers to the limit to the number of humans the earth can support in the longterm without damage to the environment.” (Giampietro, et al, 1992) The troublesome phrase here is “without damage to the environment.” One damages the environment when one kills a mosquito, builds a fire, erects a house, develops a subdivision, builds a power plant, constructs a city, explodes a nuclear weapon, or wages nuclear war. Which, if any, of these things takes place “without damage to the environment?” Although it is not stated explicitly, the term “can support” must mean “for a very long time.”

There are two ways of viewing damage to the environment. At one extreme, one could hold the view that humans are apart from the environment, so that everything humans do damages the environment. At the other extreme, one could view humans as part of the environment, so that everything humans do is a part of the course of nature and hence, by definition, is not damaging
to the environment.

Human activities have already caused great change in the global environment. May observes that (May, 1993)

…the scale and scope of human activities have, for the first time, grown to rival the natural processes that built the biosphere and that maintain it as a place where life can flourish.

Many facts testify to this statement. It is estimated that somewhere between 20 and 40 percent of
the earth’s primary productivity, from plant photosynthesis on land and in the sea, is now
appropriated for human use.  Perhaps the definition of carrying capacity means, “without further damage to the environment?” But then we note that growing populations need growing numbers of jobs and growing rates of consumption of resources. The satisfaction of these needs is almost always at the expense of the environment. So, if we do not want to do further damage to the environment, it seems logical that, as a minimum, we must stop population growth. When we talk about carrying capacity we must focus on population numbers and on the long term. This inevitably leads to a recognition of the need to stop population growth.

It is most probable that the term “carrying capacity” has to imply attaining a period of negative growth of populations, until populations and life styles reach a level that can be maintained indefinitely (sustained) by the world’s biological and physical resources. The widespread rejection of this conclusion leads one to be certain that every estimate of the number of people that constitutes the carrying capacity of a country or of the Earth will be a subject of controversy. In some cases different scientists will intrepret the data differently. In other cases the entire concept of carrying capacity will come under political and ideological attack. For example, when Jack Kemp, who was then the U.S. Secretary of Housing and Urban Development, was informed of a report from the United Nations that told of resource problems that would arise because of increasing populations, it was reported that he said, “Nonsense, people are not a drain on the resources of the planet.” (Kemp, 1992) Malcolm Forbes, Jr. Editor of Forbes Magazine had a similar response to the reports of global problems resulting from overpopulation in both the developed and underdeveloped parts of the world; “It’s all nonsense.” (Forbes, 1992) This helps make the concept of “carrying capacity” contentious and and hence an unpopular one for political leaders to embrace. None the less, carrying capacity is a vitally important concept, and it must become central to our thinking.


The U.S. Environmental Protection Agency has done many constructive and beneficial things. The policies, actions, and leadership of the Agency are crucial to any hope for a sustainable society. In a recent report we read,

In view of the increasing national and international interest in sustainable development, Congress has asked the Environmental Protection Agency (EPA) to report on its efforts to incorporate the concepts of sustainable development into the Agency’s operations.

The Report (EPA, 1993) is at once encouraging and distressing. It is encouraging to read of all of the many activities of the Agency which help protect the environment. It is distressing to search in vain through the Report for acknowledgment that population growth is at the root of most of the problems of the environment. Unlike the report of the Bruntland Commission, the EPA report avoids making the allegation that population growth is not the central problem. The EPA report makes only a very few minor references to the problems of urban population growth.

The Report speaks of an initiative to pursue sustainable development in the Central Valley of California where many areas are experiencing rapid urban growth and associated environmental problems….

A stronger emphasis on sustainable agricultural practices will be a key element in any long- tern
solutions to problems in the area.

“A stronger emphasis on sustainable agricultural practices” won’t stop “rapid urban growth and the associated environmental problems…” and hence, an emphasis on agriculture can not solve the problem. If the EPA is to address the “associated environmental problems”, it would seem to be more important to focus on stopping the “rapid urban growth” which causes the problems. Why focus on the development of “sustainable agricultural practices” when agriculture will be displaced by the “rapid urban growth.” However, if “A stronger emphasis on sustainable agricultural practices” means protect agricultural land from any further loss to developments, then perhaps there is logic to the statements quoted above.

In general, with our present social systems, agriculture, sustainable or otherwise, can’t be maintained in the face of urban population growth.

In speaking of the New Jersey Coastal Management Plan for the management of an environmentally sensitive tidal wetland, the Report says

The project involves balancing the intense development pressures in the area with wetlands wildlife protection, water quality, air quality, waste management, and other environmental considerations.

Here we are “balancing” again. In many ways, a series of balances is a way to “Sacrifice the environment in an environmentally sensitive way.”

In the Pacific Northwest

The EPA…is an active participant in these discussions, which focus on sustaining high quality natural resources and marine ecosystems in the face of rapid population and economic growth in the area.

These quotations of minor sections of the EPA report make it clear that the EPA understands the origin of environmental problems. Thus it is all the more puzzling that the Agency so carefully avoids serious discussion of the fundamental source of so many of the problems it is supposed to address.

In this report of approximately 30 pages on the Agency’s programs relating to sustainable development, the term “sustainable development” is mentioned hundreds of times, and population growth, the most important variable in the equation, is mentioned just these few times. It is as though one attempted to build a 100 story skyscraper from good materials, but one forgot to put in
a foundation.

A proposal for the establishment of a “National Institute for the Environment” (1993) is being advanced. If the proposed institute is to be effective, its mission and charge must include, “Studying the demographic causes and consequences of environmental problems.”


The pertinent definition of “sustain” is “to maintain, or to cause to continue…” The definition suggests that things can be sustained for long periods of time. Thus, when the Bruntland Report speaks of “Future generations” and “into the distant future,” it would seem to mean “for all future generations” or “forever.”

Let us be specific and state that both “Carrying Capacity” and “Sustainable” imply “for the period in which we hope humans will inhabit the earth.” This means “for many millenia.”

In what follows, “standard of living” is to be thought of in terms of the average annual per-capita consumption of goods; “carrying capacity” refers to the number of people that can be sustained. The term “resources” refers to virgin resources, while “goods” can include both virgin and recycled materials.


The laws, hypotheses, observations, and predictions that follow are offered to define the term “sustainability” which must be understood to mean, “for many millenia.” In some cases these statements are accompanied by corollaries that are identified by capital letters. They all apply for populations and rates of consumption of goods and resources of the sizes and scales found in
the world in 1994, and may not be applicable for small numbers of people or to groups in primitive tribal situations.

These laws are believed to hold rigorously.

The hypotheses are less rigorous than the laws. There may be exceptions to some, and some may be proven to be wrong. Experience may show that some of the hypotheses should be elevated to the status of laws.

The observations may shed light on the problems and on mechanisms for finding solutions to the problems.

The predictions are those of a retired nuclear physicist who has been watching these problems for several decades.

The lists are but a single compilation, and hence may be incomplete. Readers are invited to communicate with the author in regard to items that should or should not be in these lists.

In many cases, these laws and statements have been recognized, set forth, and elaborated on by others.


We start by repeating three laws of human ecology that are given by Garrett Hardin. (Hardin, 1993) These are fundamental, and need to be known and recognized by all who would speak of sustainability.

First Law: “We can never do merely one thing.”

This is a profound and eloquent observation of the interconnectedness of nature.

Second Law: “There’s no away to throw to.”

This is a compact statement of one of the major problems of the “effluent society.”

Third Law: The impact (I) of any group or nation on the environment is represented qualitatively by the relation

I = P A T

where P is the size of the population, A is the per-capita affluence, measured by per-capita consumption, and T is a measure of the damage done by the technologies that are used in supplying the consumption. Hardin attributes this law to Ehrlich and Holdren. (Ehrlich and Holdren, 1971)

The suggestion may be made that the Third Law is too conservative. The Third Law suggests that I varies as Pn where n = 1. There are situations where the impact of humans increases more rapidly than linearly with the size of the population P so that n > 1.


These theorems are from the work of the eminent economist Kenneth Boulding. (Boulding, 1971)

First Theorem: “The Dismal Theorem” “If the only ultimate check on the growth of population is misery, then the population will grow until it is miserable enough to stop its growth.”

Second Theorem: “The Utterly Dismal Theorem” This theorem “states that any technical improvement can only relieve misery for a while, for so long as misery is the only check on population, the [technical] improvement will enable population to grow, and will soon enable more people to live in misery than before. The final result of [technical] improvements, therefore, is
to increase the equilibrium population which is to increase the total sum of human misery.”

Third Theorem: (“The moderately cheerful form of the Dismal Theorem”) “Fortunately, it is not too difficult to restate the Dismal Theorem in a moderately cheerful form, which states that if something else, other then misery and starvation, can be found which will keep a prosperous population in check, the population does not have to grow until it is miserable and starves, and it can be stably prosperous.”

Boulding continues, “Until we know more, the Cheerful Theorem remains a question mark. Misery we know will do the trick. This is the only sure-fire automatic method of bringing population to an equilibrium. Other things may do it.”


First Law: Population growth and/or growth in the rates of consumption of resources cannot be sustained.

A) A population growth rate less than or equal to zero and declining rates of consumption of resources are necessary, but are not sufficient, conditions for a sustainable society.

B) Unsustainability will be the certain result of any program of “development,” whether or not it is said to “sustainable,” that ignores the problem of population growth and that does not plan the achievement of zero or a period of negative growth of populations and of rates of consumption of resources.

C) The research and regulation programs of governmental agencies that are charged with protecting the environment and promoting “sustainability” are, in the long run, irrelevant unless these programs address vigorously and quantitatively the determination of carrying capacities and unless the programs study in depth the demographic causes and consequences of environmental problems.

D) Societies, or sectors of a society, that depend on population growth or growth in their rates of consumption of resources, are unsustainable.

E) Persons who advocate population growth and/or growth in the rates of consumption of resources are advocating unsustainability.

F) Persons whose actions directly or indirectly cause increases in population or in the rates of consumption of resources are moving society away from sustainability. (Advertising your city or state as an ideal site in which to locate new factories indicates a desire to increase the population of your city or state.)

G) The term “Sustainable Growth” is an oxymoron.

Second Law: In a society with a growing population and/or growing rates of consumption of resources, the larger the population, and/or the larger the rates of consumption of resources, the more difficult it will be to transform the society to thecondition of sustainability.

Third Law: The response time of populations to changes in the total fertility rate is the length of time people live from their child-bearing years to the end of life, or approximately fifty years. (This is called “population momentum.”)

A) If we want the population sizes to be reduced or at least stabilized by the mid-21st century, we must make the necessary changes in the total fertility rates before the end of the 20th century.

B) The time horizon of political leaders is of the order of two to eight years.

C) It will be difficult to convince political leaders to act now to change course, when the full results of the change may not be apparent in those leaders’ lifetimes.

Fourth Law: The size of population that can be sustained (the carrying capacity) and the sustainable average standard of living of the population are inversely related to one another.

A) The higher the standard of living one wishes to sustain, the more urgent it is to stop population growth.

B) Reductions in the rates of consumption of resources and reductions in the rates of production of
pollution can shift the carrying capacity in the direction of sustaining a larger population.

Fifth Law: Sustainability requires that the size of the population be less than or equal to the carrying capacity of the ecosystem for the desired standard of living.

A) Sustainability requires an equilibrium between human society and dynamic but stable ecosystems.

B) Destruction of ecosystems tends to reduce the carrying capacity and/or the sustainable standard of living.

C) The rate of destruction of ecosystems increases as the rate of growth of the population increases.

D) Population growth rates less than or equal to zero are necessary, but are not sufficient, conditions for halting the destruction of the environment.

Sixth Law: (The lesson of “The Tragedy of the Commons”) (Hardin,1968):

The benefits of population growth and of growth in the rates of consumption of resources accrue to individuals; the costs of population growth and growth in the rates of consumption of resources are borne by all of society.

A) Individuals who benefit from growth will continue to exert strong pressures supporting and encouraging both population growth and growth in rates of consumption of resources.

B) The individuals who promote growth are motivated by the recognition that growth is good for them. In order to gain public support for their goals, they must convince people that population growth and growth in the rates of consumption of resources, are also good for society. This is the Charles Wilson argument: if it is good for General Motors, it is good for the United States. (Yates, 1983)

Seventh Law: Growth in the rate of consumption of a non-renewable resource, such as a fossil fuel, causes a dramatic decrease in the life-expectancy of the resource.

A) In a world of growing rates of consumption of resources, it is seriously misleading to state the life-expectancy of a non-renewable resource “at present rates of consumption,” i.e., with no growth.

B) It is intellectually dishonest to advocate growth in the rate of consumption of a non- renewable resource while, at the same time, reassuring people about how long the resource will last “at present rates of consumption.”

Eighth Law: The time of expiration of non-renewable resources can be postponed, possibly for a very long time, by

i) technological improvements in the efficiency with which the resources are recovered and used

ii) using the resources in accord with a program of “Sustained Availability,” (Bartlett, 1986)

iii) recycling

iv) the use of substitute resources.

Ninth Law: When large efforts are made to improve the efficiency with which resources are used, the resulting savings are easily and completely wiped out by the added resource needs that arise as a consequence of modest increases in population.

A) When resources are used more efficiently, the consequence often is that the “saved” resources are not put aside for the use of future generations, but instead are used immediately to encourage and support larger populations.

B) Humans have an enormous compulsion to find an immediate use for all available resources.

Tenth Law: The benefits of large efforts to preserve the environment are easily canceled by the added demands on the environment that result from small increases in human population.

Eleventh Law: (Second Law of Thermodynamics) When rates of pollution exceed the natural cleansing capacity of the environment, it is easier to pollute than it is to clean up the environment.

Twelfth Law: (Eric Sevareid’s Law); The chief cause of problems is solutions. (Sevareid, 1970)

A) This law should be a central part of higher education, especially in engineering.

B) Solutions of neighborhood problems cause city problems:

Solutions of city problems cause county problems:

Solutions of county problems cause regional problems:

Solutions of regional problems cause statewide problems:

Ad infinitum

Thirteenth Law: Humans will always be dependent on agriculture.

A) Supermarkets alone are not sufficient.

B) The central task in sustainable agriculture is to preserve agricultural land. The agricultural land must be protected from losses due to things such as

i) Urbanization and development

ii) Erosion

iii) Poisioning by chemicals

Fourteenth Law: If, for whatever reason, humans fail to stop population growth and growth in the rates of consumption of resources, nature will stop these growths.

A) Nature’s method of stopping growth is cruel and inhumane.

B) Glimpses of nature’s method of dealing with population that have exceeded the carrying capacity of their lands can be seen each night on the television news reports from places where large populations are experiencing starvation and misery.

Fifteenth Law: Starving people don’t care about sustainability.

A) If sustainability is to be achieved, the necessary leadership and resources must be supplied by people who are not starving.

Sixteenth Law: The addition of the word “sustainable” to our vocabulary, to our reports, programs, and papers, and to the names of our academic institutes and research programs, is not sufficient to ensure that our society becomes sustainable.

Seventeenth Law: Extinction is forever.


1) For the 1994 average global standard of living, the 1994 population of the Earth exceeds the carrying capacity of the Earth.

2) For the 1994 average standard of living in the United States, the 1994 population of the United States exceeds the carrying capacity of the United States. (Abernethy, 1993), (Giampietro and Pimentel, 1993)

3) The increasing sizes of populations that result from population growth are the single greatest and most insidious threat to representative democracy.

4) The costs of programs to stop population growth are small compared to the costs of population increases.

5) For society as a whole, population growth never pays for itself. (This is a consequence of the Tragedy of the Commons.)

A) In the U.S. in general, the larger the population of a city, the higher are the municipal per-capita annual taxes.

6) The time required for a society to make a planned transition to sustainability on its own terms, so it can live within the carrying capacity of its ecosystem, increases with increases in

i) the size of its population

ii) the rate of growth of its population

iii) the society’s average per-capita rate of consumption of new resources.

7) The rate (S) at which a society can improve the average standard of living of its people is directly related to the rate of application of new technologies (T) and is inversely related to the rate of growth (R) of the size of the population (the fractional increase per unit time), by a relation with the general properties of the equation,

S = T – A R + B

where A and B are positive constants.

A) In places in the world in 1994, the value of R (the rate of growth of population) is so large that it is causing S to be negative. Said in other words,

a) Population growth competes with and slows down the rate of improvement of the average standard of living and may cause the average standard of living to decline. In other words,
b) Population growth interferes with economic growth.

8) Social stability is a necessary, but not a sufficient, condition for sustainability.

A) Human freedoms depend on social stability.

B) Armed conflict (war) cannot be a part of a sustainable society.

9) In some cases, social stability tends to be inversely related to population density.

10) The per-capita burden of the lowered standard of living that generally results from population growth and from the decline of resources falls most heavily on the poor.

11) When populations are growing, the rate of growth of the fraction of the population that is poor exceeds the rate of growth of the fraction of the population that is wealthy.

12) Environmental problems cannot be solved or ameliorated by increases in population or by increases in the rates of consumption of resources.

A) Probably all environmental problems would be easier to solve if the population were smaller and/or if the rates of consumption of resources were smaller.

13) Problems of shortages of non-renewable resources cannot be solved or ameliorated by population growth.

14) In general, the environment cannot be enhanced or even preserved through compromises.

A) Compromises and accommodations between the immediate needs of people and the long-term needs of the environment will generally be resolved in favor of people. For the most part, compromises only reduce the rate of destruction of the environment or they increase the elegance with which the environment is destroyed.

15) The fractional rate of destruction of the environment that results from human activities will always exceed the fractional rate of increase of our knowledge and understanding of the environment.

A) Every decision affecting the environment will have to be made with less than full knowledge of the risks and consequences of the decision.

B) Much of our knowledge of the environment has come from the study of past mistakes.

C) It will always be possible for persons to delay the implementation of corrective measures, claiming that our information about the problems is incomplete.

16) By the time overpopulation and shortages of resources are obvious to most people, the carrying capacity has been exceeded. It is then almost too late to think about sustainability.

A) It is difficult to know what to do once one realizes that the population is too large.

B) Long-range thinking, planning, and leadership, carried out with a full recognition of the laws of nature, is most urgently needed.

17) Importing non-renewable natural resources demonstrates unsustainability; exporting non- renewable natural resources reduces the ultimate sustainable standard of living and/or the carrying capacity of the exporting country.

18) Because of the universal nature of world trade, the concept of “carrying capacity” is difficult to apply to a nation or region.

A) Sustainability is a global problem.

B) The approach to stainability must be sought on the local and national levels.

C) If a local official speaks of his/her community being sustainable, it probably is not true.

19) Sustainable agriculture cannot be based on large annual energy inputs from fossil fuels, and in particular from petroleum.

i) “The food system consumes ten times more energy than it provides to society in food energy.” (Giampietro and Pimentel, 1993)

20) Irrigation of farmland, as it has been practiced throughout history and up to the present time, cannot be sustained. (Abernethy, 1993, p.136)

i) The lands become poisoned with salts.

21) Hydroelectric power generated from reservoirs created by construction of large dams, cannot be sustained.

i) The reservoirs fill with silt.


1) The first and most important effort that must be made in order to move toward a sustainable society is to stop population growth. This will require the initiation of major comprehensive educational, technical, and outreach programs in the areas of social responsibility, contraception, family planning, and immigration control. The greater the degree to which themcarrying capacity has been exceeded, the more probable it is that coercion will become a factor in these programs.

2) The food chain is nature’s equilibrium mechanism. It functions to prevent unlimited expansion of populations of flora and fauna. Primitive human societies were able to maintain approximately constant populations and to live within the carrying capacity of their ecosystems. The methods used were often cruel and inhumane. Technology has given many people the feeling that humans are exempt from the constraint of limited carrying capacities.

3) Ancient civilizations have vanished, in part because they grew too large and their size exceeded the carrying capacity of the ecosystems on which they depended for support.

a) Civilizations today show considerable tendency to repeat the mistakes of earlier civilizations, but on a much larger scale.

4) The complete era of the use of fossil fuels by humans will be a vanishingly short fraction of the span of human existence on the Earth.

5) The supplies of all non-renewable resources will effectively expire when the costs (in cash, in energy, in ecological and societal disruption) of making available a quantity of the resource exceed the value of the quantity of the resource.

6) Comprehensive educational, technical, and outreach programs in the areas of efficient use of resources will be needed in order to help achieve sustainability.

7) A major use of technology is, and has been, to accommodate the growth of populations, and to remove the recognition of the importance of living within the carrying capacity of the environment. (See Boulding’s Utterly Dismal Theorem and Eric Sevareid’s Law)

A) This use of technology has had the effect of encouraging population growth.

B) This use of technology inhibits an approach to sustainability.

C) An essential condition for sustainability is that technology be redirected toward the improvement of the quality of life and away from its use to increase the quantity of life.

8) Creating jobs increases the number of people out of work.

In a city or state, creating jobs increases the population, of which 5% to 7% are always unemployed. It follows that the increase in population that is the result of the creation of jobs is always reflected as an increase in the number of people out of work. This is the direct consequence of the ease with which people can move from places with high unemployment to places with low unemployment. In this regard, the movement of people is like the movement of molecules of an ideal gas, that tend to move until they achieve a constant pressure throughout a closed vessel.

A) If it is desired to maintain an “island” of low unemployment, in a nation, a state, or a community, one must erect barriers to prevent the in-migration of unemployed people.


1) Coal and/or oil shale, may last 200 years. Other fossil fuels probably will not be available in globally significant quantities for more than a few decades into the 21st century.

2) If replacements can be found for fossil fuels, especially for petroleum, it will require major technological breakthroughs.

3) Technological progress in the future is much more likely to be characterized by incremental advances than by breakthroughs, especially in the field of sources of energy.

4) The probability is very small that technological developments will produce new sources of energy in the next century, sources not already known in 1994, that will have the potential of supplying a significant fraction of the world’s energy needs for any appreciable period of time.

5) The larger the global total daily demand for energy, the smaller is the probability that a new energy source or technology will be found that will have the potential of being developed sufficiently to meet an appreciable fraction of the global daily energy demand for any extended period of time.

6) The larger the global total daily demand for energy, the longer is the period of time that will be required for a new energy technology to be developed to the point where it will have the capacity of meeting an appreciable fraction of the global daily energy demand.

7) In the event that science and technology find a new source of large quantities of energy, the probability is high that the new source will be technologically very complex, with the result that it will be extremely costly to bring globally significant quantities of the new energy to the marketplace.

8) Children born in 1990 will not live to see 10% of the energy consumed in the U.S. generated by terrestrial nuclear fusion.
(Bartlett, 1990)

9) There will always be popular and persuasive technological optimists who believe that population increases are good, and who believe that the human mind has unlimited capacity to find technological solutions to all problems of crowding, environmental destruction, and resource shortages.

A) These technological optimists are usually not biological or physical scientists.

B) Politicians and business people tend to be eager disciples of the technological optimists.

10) Because population growth is only one of the factors that drives up the cost of living, the rate of increase of the cost of living will probably be larger than the rate of increase of population.


1) Local and regional business and political leaders will continue to spend much of their time trying to attract new industries and populations to their areas, and to spend a prominent few minutes a week complaining and wondering what to do about the increasing pollution, congestion, crime, costs, etc.

2) Local and regional political and business leaders will continue to use the circular arguments of self- fulfilling predictions in order to generate local population growth. These are the steps in the cycle.

i) Quantitative projections of future population growth in the area are made.

ii) Plans are made to expand the municipal or regional infrastructure to accomodate the predicted growth.

iii) Bonds are issued to raise money to pay for the planned expansions of the infrastructure, and the infrastructure is expanded.

iv) The bonds must be paid off on a schedule that is based on the projections of population growth.

v) The political and business leaders will do everything in their power to make certain that the projected population growth takes place, so that the bonds can be paid off on schedule.

vi) When this results in the needed population growth, the leaders will speak loudly of their foresight.

vii) Go back to i) and repeat.

3) Some political and business leaders will continue to want to throw away all manner of toxic waste by dumping it on the lands of low-income or underdeveloped people, in the U.S. or abroad.

4) Some business leaders will want to continue to manufacture hazardous materials whose sale in the U.S. is prohibited, so that these materials can be sold abroad.

5) Business and political leaders will continue to find it more attractive to promote growth than to promote sustainability.

A) It is easy to talk about sustainability.

B) It is difficult to make realistic constructive progress toward sustainability

C) Business and political leaders are not attracted to the concept of a “carrying capacity.”

6) In the U.S., political “conservatives” will continue to be liberal in their policy recommendations in regard to rapid exploitation and use of the earth’s renewable and non-renewable resources, with complete confidence that technology will be able to solve all of the consequent problems of shortages, pollution, and environmental degradation. Political “liberals” will continue to urge people to be conservative, to conserve and to protect the environment, to recycle, to use energy more efficiently, etc.

7) Entrepreneurs and politicians will continue to use the term “sustainable” for their own personal advantage in promotion of enterprises and programs, whether or not these enterprises and programs are sustainable or contribute to the creation of a sustainable society.


The challenge of making the transition to a sustainable society is enormous, in part because there are so many aspects of the problem. If one glances through Agenda 21, The Earth Summit Strategy to Save Our Planet, one is overwhelmed by the sheer number of pages of recommendations, “We must do this,” “We must do that,” etc. The book does avoids the population problem, even though the authors have to know that population growth is the central and most fundamental human problem. Agenda 21 seems to be a diversion to keep people from recognizing the centrality of population growth to the enormous problems of the U.S. and the world. The immediate task is to get the population program back at the top of the national and global agendas.

The year 1992 was the year of the United Nations Conference on Environment and Development, the Earth Summit, that was held in Rio de Janerio. The year also marked the end of a long period of dangerous withdrawal of the U.S. from its active support of family planning programs throughout the world. This long period was characterized by the belief that the human mind could use technology to overcome all limits, so that carrying capacity was not an issue, and population increases should be welcomed rather than avoided. (Bartlett, 1985)

There are signs now that things have changed for the better and that there is a recognition in the top echelons of governments that population is the problem. The Mid-Atlantic Preparatory Consultation meeting in Airlie, Virginia urged the 1994 International Conference on Population and Development in Cairo, Egypt to focus on a number of important topics, including

A clear statement of the linkages between population, environment, economic growth and
sustainable development. (Popline, 1993)

President Fidel Ramos of the Phillipines delivered the keynote address at a workshop for implementing the Rio Earth Summit’s Agenda 21 in the Phillipines. (Ramos, 1993)

I believe that…the serious imbalance that today threatens the sustainability of both our economy and our environment has arisen primarily from our pervasive and proliferating population growth.

There are many encouraging signs from communities around the U.S. that indicate a growing awareness of the local problems of continued unrestrained growth of populations. It has been noted that creating jobs increases the number of people out of work, and that population growth in our communities never pays for itself. Taxes and utility costs must escalate in order to pay for the growth. For example, in the U.S., it costs the order of $15,000 per pupil to build a new school building. If each new home has, on the average, 0.4 school-age children, then each new house that is built creates the need for about $6000 of tax money for school construction. In addition, growth brings increased demands on all municipal utilities and brings increased levels of congestion, frustration, and air pollution.

In recent years, several states have seen taxpayer revolts in the form of ballot questions that were adopted to limit the allowed tax increases. These revolts were not in decaying rust-belt states, the revolts have been in the states that claimed to be the most prosperous because they had the largest rates of population growth. Unfortunately, these limitations on taxation, that were made necessary by population growth, and that were intended to stop or slow the increase of taxes, have not stopped the population growth which was the root cause of much of the increase in taxes.

At the local or state levels, there is an interesting parallel between the promotion of growth and the promotion of war. The waging of war is the sole enterprise of large military establishments. Even the lowest mind knows what has to be done to win a war; “One has to beat the opponent,” after which one can have a large party to celebrate the victory, and then one starts preparing for the next war. Promoting community growth is quite similar. The promotion of growth is the sole enterprise of large
municipal and state establishments. It does not take much of a mind to know that growth requires that you beat some competing community in the effort get new factories to come to your community. Campaigns and battles are planned, and, when a factory comes, you can have a large party to celebrate the victory, after which, you start looking for new factories.

In contrast, winning the peace is quite different. Even the best minds don’t know for sure what is the best way to “win the peace.” There is no large public establishment that is devoted to or has a vested interest in maintaining the peace. There is noterminal point at which a party is in order where we can celebrate the fact that, “We won the peace!” Winning the peace takes eternal vigilance. Protecting the community environment is quite parallel. The best minds don’t know for sure the best way to do it. There are few public establishments whose sole role is to preserve the environment. One can postpone assaults on the environment, but by and large, it takes eternal vigilance of concerned citizens, who, at best, can only reduce the rate of loss of the environment. There is no terminal time at which one can have a party to celebrate that, “We have saved the environment!”

How do we work on the local problem? Many years ago I was discussing population growth of Boulder with a prominent member of the Colorado Legislature. At one point he said,

“Al, we could not stop Boulder’s growth if we wanted to!”

I responded,

“I agree, therefore let’s put a tax on the growth so that, as a minimum, it pays for itself, instead of having to be paid for by the existing taxpayers.”

His response was quick and emphatic.

“You can’t do that, you’d slow down our growth!”

His answer showed the way. On the community level in the U.S., we should work to make growth pay for itself. The Tragedy of the Commons makes it clear that there will always be large opposition to programs of making population growth pay for itself. The promoters of growth will use their considerable resources to convince the community that the community should pay the costs of growth. In our communities, making growth pay for itself could be a major factor in slowing and
possibly stopping the population growth.

On the local and national levels, we need to work to improve social justice and equity. The series of big city riots of the recent decades are symptoms of a deep-seated illness that we have ignored too long. The illness is certainly made worse by the rapid population growth that consumes public and private resources in order to give minimal accomodation to the growth. The resources that are used to support the growth are taken away from all manner of community programs that are essential for improving education, justice, and equity. Injustice and inequity breed unrest and discontent. When a condition of instability is reached, things can happen with surprising speed. We were all stunned by the swiftness of the fall of the Soviet Union.

On the national scale, we can hope for leaders who will recognize that population growth is a major problem in the U.S. With a lot of work at the grassroots, our system of representative government will respond.

As we enter an era of expanded global trade, we need to know that the ease of international trade serves to block out our recognition of the concept of “carrying capacity.” These other countries with which we trade with such ease seem to provide an “away” from which we can get resources and to which we can later throw things made from those resources. International trade interferes with our understanding of the concept of limits.

On the global scale, we need to support family planning throughout the world, and we should restrict our foreign aid and send it only to those countries that make continued demonstrated progress in reducing population growth rates. Kenneth Boulding observed that, “The economic analysis I presented earlier indicates that the major priority, and one in which the United Nations
can be of great utility, is a world campaign for the reduction of birth rates. This, I suggest, is more important than any program of foreign aid and investments. Indeed, if it is neglected, all programs of aid and investment will, I believe, be ultimately self-defeating and will simply increase the amount of human misery.” (Boulding, 1971, p.361)

If we work on the problem of population growth in our communities, counties, and states, it is possible that our leaders in Washington, D.C. will get the message and follow the people. There is reason to be optimistic.

In writing about the essay of Malthus on population, Boulding observes that the essay, “punctures the easy optimism of the utopians of any generation. But by revealing the nature of at least one dragon that must be slain before misery can be abolished, its ultimate message is one of hope, and the truth, however unpleasant, tends ‘not to create despair, but activity’ of the right
kind.” (Boulding, 1971, p.142)


When competing “experts” recommend diametrically opposing paths of action regarding resources, carrying capacity, sustainability, and the future, we serve the cause of sustainability by choosing the conservative path. This is the path that would leave society in the less precarious position if the path we choose turns out to be the wrong path.


I am greatly indebted to Profs. Robert Ristinen and Charles Southwick for their critical reading of this manuscript and to Prof. Ulrich Muller-Herold, and Juliet Serenyi for their very helpful suggestions.


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