Albert A. Bartlett
Part One: Introduction & Overview


In the period since this paper was first published ( Bartlett 1994 ), reprints have been widely distributed. Since then the author has received no communications suggesting that this paper contained errors. This could indicate that either readers have found the paper to be reasonable, or that they believe it is so completely wrong as to be unworthy of criticism.

The main message of the paper is contained in the first two Laws of Sustainability, which point out that in any society, population growth cannot be sustained, and that the larger the population, the more difficult it will be for the society to achieve sustainability.

The Brundtland Report ( Brundtland 1987 ) is, in 1998, more than a decade old. The definition of sustainability given in that report remains the definition that is frequently cited by persons writing and speaking of sustainability.

Many parts of the original paper have been revised and updated, but the Laws, Hypotheses, Observations and Predictions relating to sustainability have had only minor revisions and additions.


The related terms, "sustainable" and "sustainability" are popularly used to describe a wide variety of activities which are generally ecologically laudable but which may not be sustainable. An examination of major reports reveals contradictory uses of the terms. An attempt is made here to give a firm and unambiguous definition to the concept of sustainability and to translate the definition into a series of laws and hypotheses which, it is hoped, will clarify the implications of the use of the concept of sustainability. These are followed by a series of observations and predictions that relate to "sustainability." The laws should enable one to read the many publications on sustainability and help one to decide whether the publications are seeking to illuminate or to obfuscate.


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, was the book Limits to Growth ( Meadows, 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 is used to describe agriculture and forestry when these enterprises are conducted in such a way that they could be continued indefinitely, i.e., their yield could be sustained. The introduction of the word "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, with little visible change, "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. In the manner of Alice in Wonderland, and without regard for accuracy or consistency, "sustainability" seems to have been redefined flexibly to suit a variety of wishes and conveniences.



First, we must accept the idea that "sustainable" has to mean "for an unspecified long period of time."

Second, we must acknowledge the mathematical fact that steady growth ( a fixed percent per year ) gives very large numbers in modest periods of time. For example, a population of 10,000 people growing at 7 % per year will become a population of 10,000,000 people in just 100 years. ( Bartlett 1978 )

From these two statements we can see that the term "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 the most fundamental truth of sustainability:

When applied to material things,

the term "sustainable growth" is an oxymoron.

( One can have sustainable growth of non-material things such as inflation. )

Daly has pointed out that "sustainable development" may be possible if materials are recycled to the maximum degree possible, and if one does not have growth in the annual material throughput of the economy. ( Daly 1994 )


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 exists that the frequent 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. Politicians have gotten into the act. 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. The governorís charge has the effect of increasing the stateís production of greenhouse gases ( a move away from sustainability ) and thus increasing the stateís contribution to global warming. In some cases, these big-time operations may be illustrative of what might be called the "Willie Sutton school of research management." ( Sutton )

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."

The term "sustainable growth" is used by our political leaders even though the term is clearly an oxymoron. 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 )

We even find a scientist writing about "sustainable growth:"

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

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 oxymoronic.

This wide spectrum of uses 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? Unfortunately, the answer seems to be "No."

Let us examine the use of the term "sustainable" in some major environmental reports.



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, 1972 ). A great increase of awareness came with the publication of the report of the United Nations World Commission on Environment and Development, the Brundtland Report, which is available in bookstores under the title Our Common Future. ( Brundtland 1987 )

In graphic and heart-wrenching detail, the 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". One has to ask if it is possible to have an increase in ecomomic activity ( growth ) 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? What is meant by the undefined terms, "socially sustainable" and "environmentally sustainable?" Can we have one without the other?

As we have seen, these two concepts of "growth" and "sustainability" are in 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. "Population size and growth" are vaguely identified as possible problem areas, but we donít know what the Commission means 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. [ emphasis added ]

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 undefined "extreme rates of population growth" 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: we see no recognition that enormous technical and economic difficulties can reasonably be expected in the search for an "environmentally sound and economically viable energy pathway." Most important here is the 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 Reportís definition of "sustainable development" has been widely used by others. It appears in the first sentence of Chapter 2, ( p. 43 ):

Sustainable development is development that meets the needs of the present without compromising the 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," are crucial for an understanding 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, even though it is obvious that non-renewable resources consumed now will not be available for consumption by future generations.

The Commission 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 for the problems 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 of the decline of "global productive potential of ecosystems" due to deforestation, the loss of topsoil, pollution, etc., ( Kendall and Pimentel 1994 ) 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 are thought to be representative of the vague and contradictory messages that are in this important report. As the Report seeks to address severe global problems, it clearly tries to marginalize the role of population size as an agent of causation of these problems.

The Brundtland Commission Report's discussion of "sustainability" is both optimistic and vague. The Commission probably felt that the discussion had to be optimistic, but given the facts, it was necessary to be vague and contradictory in order not to appear to be pessimistic.

Straight talk about the meaning of "sustainability" was similarly avoided in a more recent report that came out of the 1992 Earth Summit in Rio de Janeiro, 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 published version of 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?" "Controlling world population growth" could mean, "hold the annual population growth rate at its 1993 value of approximately 1.6 % per year," which surely was not their intent. Why does the Report use the phrase "controlling world population growth" when one suspects that the Reportís authors 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 to set forth clearly the known concrete details of "the impact of population growth on the Earth?"

Then, under the Reportís 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 Report indicates a recognition of the fact 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 Report fails to do the exploring. The Report could have educated its readers about the "long-term consequences of continued population growth" and then could have identified for the readers the appropriate remedial courses of action which are necessary to achieve zero growth of population as rapidly as possible. But to negate it all, the Report refers to the "inevitable increase in population numbers." Thus the Report seems to say that nothing can be done. This leads to the question, "If nothing can be done, why bother to educate people about the Ďlong-term consequences of continued population growthí?"

This Report is loaded with admonitions suggesting that we all go out and embark on programs that are sustainable. In enumerating the things that the Report suggests have to be done, the Report has both the comprehensive scope and the literary style of the Yellow Pages. The Report 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 education of women, distribution of resources, justice, and simple equity.

The failure of the Report to address the population problem was underscored by Robert 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 Janeiro. Until this changes, I see little hope.



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 long term 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?"

The concept of carrying capacity is central to discussions of population growth. Since the publication of the original paper, the concept has been examined by Cohen in a book How Many People can the Earth Support? ( Cohen 1995 ) Cohen makes a scholarly examination of many past estimates of the carrying capacity of the Earth, and concludes that it is not possible to say how many people the Earth can support. Furthermore, any calculated estimate of the carrying capacity of the Earth may be challenged and will certainly be ignored.

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.

An impact on the global environment of this magnitude is properly the cause for alarm.

We note that growing populations require growing numbers of jobs and growing rates of consumption of resources, and the satisfaction of these requirements is almost always at the expense of the carrying capacity of the environment.

The inevitable and unavoidable conclusion is that if we want to stop the increasing damage to the global environment, as a minimum, we must stop population growth.

It wonít be easy. 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 if we are to maintain the carrying capacity of the Earth. ( 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 problems.

So, instead of trying to calculate how many people the Earth can support, we should instead, focus on the question of why should we have more population growth. This is nicely framed in the challenge:

Can you think of any problem, on any scale, from microscopic to global,

Whose long-term solution is in any demonstrable way,

Aided, assisted, or advanced, by having larger populations

At the local level, the state level, the national level, or globally?



There are prominent political leaders who believe that there is no population problem.

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 )

Here are two presidential people who reject the notion of limits that are implied by the concept of sustainability. Their expressions are consistent with a prominent refrain in presidential politics: "We can grow our way out of the problems."

Contrast these two statements with the words of the biologist E.O. Wilson who has written that:

The raging monster upon the land is population growth. In its presence, sustainability is but a fragile theoretical construct. To say, as many do, that the difficulties of nations are not due to people but to poor ideology or land-use management is sophistic.

Part Two: Population, Environment & Pseudo Solutions
Part Three: Democracy, Economy & Trade
Part Four: Laws of Sustainability
Part Five: Where Do We Go From Here?
Acknowledgements & References

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