Mankind lives on a planet endowed with a finite quantity of resources necessary to the maintenance of life. Each man, in the process of living, consumes or destroys beyond the possibility of recovery some minute portion of these resources. Eventually, the billions of men who now and in the future occupy the Earth will have used up so much of the Earth’s resources that human life will be reduced to a subsistence level for a diminishing population struggling for bare existence.
This, in a few words, is the physical basis of “The Predicament of Mankind,” as described in The Limits to Growth, published earlier this year. Its theme may well be stated as “the end of the world, as we know it, is closer than you think.”
Now the idea that the world may come to an end is not new. From the days of ancient history, prophets have threatened a horrible end as punishment to errant peoples who will not reform their ways. Visionaries have enticed their followers with promises of a new and better world to come. Philosophers have speculated upon the possibilities. Science has made nuclear holocaust a present danger.
The Limits of Growth, however, is not written in such apocalyptic terms. It invokes no supernatural forces or sudden cataclysms. It does, as befits any respectable study today, summon the computer to its aid in reaching the grim conclusion that unless the world soon changes its ways, we are headed for supervening disaster before the end of the next century. The study does not leave us without hope. Like the prophets of old, it tells us that the way to salvation is difficult and calls for basic reform and sacrifice.
The study was sponsored by the Club of Rome, a hitherto largely unknown informal organization of individuals founded in 1968 by Dr. Aurelio Peccei, an Italian industrial manager and economist. The members are an international group consisting largely of industrial experts, economists, research leaders, and scientists. With one known exception, none of them hold elective office. Its announced purposes are to foster understanding of the global system in which we live, to bring that understanding to the attention of policy-makers and the public, and thus to promote new policy initiatives and action.
Early discussions among members of the Club led to an ambitious undertaking to examine a complex of problems described as: “poverty in the midst of plenty; degradation of the environment; loss of faith in institutions; uncontrolled urban spread; insecurity of employment; alienation of youth; rejection of traditional values; and inflation and other monetary and economic disruptions.” These were regarded as components of a “world problématique” which interact in ways not understood, making solutions beyond the present capability of men and their institutions. The word “problématique” seems to be a French noun derived from the same source as our adjective “problematic,” one definition of which is: difficult to solve, or come to a decision about or to deal with. In this light, the word “problématique” seems well chosen.
The Limits of Growth was commissioned by the Club of Rome to report on Phase One of its project. This was a study, conducted by an international team under the direction of Professor Dennis Meadows of the Massachusetts Institute of Technology, employing a technique known as System Dynamics to develop the implications of a global model dealing with certain specific components of the problématique. Specifically, the study deals with five major factors: population, industrial production, agricultural production, natural resources, and pollution.
The significant, and familiar, fact about world population is that it is growing, and, furthermore, that the growth is exponential. Recent trends suggest that the growth is at a rate of 2.1% per year, which seems like a relatively modest figure, but a constant annual rate of 2.1%, being applied to a larger base each successive year, means that the population will double in about 33 years and multiply by eight times in a century. Even so, the consequences may not be sufficiently obvious without further illustration.
Suppose that the population reaches a point where it is one-half of the maximum that the world can reasonably sustain. Then, if growth continues at the 2.1% rate, there are only 33 years left to make changes in the world systems to prevent resources from becoming inadequate for the population.
Population is, of course, not independent of the other factors in the world systems, but the point is that existing processes and interactions may not be sufficient to put tolerable controls on population. Starvation is certainly not one of the controls we would willingly accept, though it is not a negligible factor today.
Industrial output is another world quantity that has been increasing exponentially, and at a much faster rate than population. The average growth rate from 1963 to 1968 was 7% per year or 5% per year on a per capita basis. This growth accounts for a substantial increase in the material standard of living of the world’s people, but this increase is very unevenly distributed. India, for example, shows very little growth, whereas the United States shows very rapid growth.
The possibilities for population growth and industrial growth are limited, in the end, by the capacity of the physical environment to supply the demands made upon it. Food is, of course, a basic requirement for survival, and an exponentially growing population will require an exponentially growing food supply. The problem was described by Thomas Malthus almost 175 years ago, but he did not foresee the developments that would let the world ignore him for a long time. In fact, the problem has only receded; it has not disappeared.
The primary resource necessary for producing food is land, and The Limits of Growth finds that we are presently using about half of the maximum area that might be brought under cultivation to maintain a questionably adequate average level of nourishment. The remaining half will require substantial capital inputs for clearing, irrigation, and fertilization to bring it into production, but we will need all of it about 33 years from now to maintain the present per capita food supply, if population continues to grow and average food production per acre remains the same. Quadrupling the productivity per acre would provide for another 66 years of population growth. Even so, these figures do not allow for people’s need for “standing room.” Housing, roads, and other essentials currently use land at the rate of one acre for each five persons. At this rate, before a hundred years have elapsed, we will need as much living and “standing room” space as we now cultivate.
How many people the world can feed depends on the level of nutrition we wish to maintain. The world average now is only one-half that of the United States. The world food capability is also dependent on the amount of capital and resources we devote to food production. Any improvement in nutritional levels and any increase in the number of people that can be fed will accelerate the use of natural resources, which are not unlimited.
The Club of Rome’s study lists a number of the more important mineral and fuel resources and shows how known global reserves relate to current annual use and to projected use. Iron, for example, is given as the metal in most generous supply. Known reserves are 240 times 1970 use. The projected rate of growth of use of iron is 1.8%, which means that present reserves could be exhausted in 93 years. If we assume that new discoveries will multiply present known reserves fivefold, iron reserves would last for 173 years. Compared to the 173 years for iron, we have only 55 years for aluminum, 48 for copper, and 29 for gold, all on the basis of reserves five times those now known. Using the same method for fuels, we find 150 years for coal, 50 years for petroleum, and 49 years for natural gas.
None of these figures, however, should be taken as a prediction. The Limits of Growth model postulates that at first, the ores and fuels that are more accessible and easily treated will be used. As these become exhausted, costs will rise because more and more labor and other resources will have to be put into production and transportation. Technological advances may hold down prices for a time, but they will eventually rise to a point that discourages consumption and encourages the use of substitutes. In the end, costs will become so high that extraction of the resource ceases, and usage drops to zero with about 5% of the reserves remaining in the Earth. The model, therefore, does not predict a constantly increasing usage rate but a bell-shaped pattern, increasing to a peak and then declining.
There is one more major aspect of man’s relation to the world to be considered in order to follow the Limits of Growth thesis. This deals with the adverse effects man imposes on his environment by his discards and waste discharges, or, in a word, pollution. Pollution seems to be increasing exponentially, and this may be explained simply by the fact that population and industrial output are increasing exponentially. How far this growth can continue without serious consequences to man is still unknown.
The danger arising from this ignorance of the limits is compounded by two characteristics of pollutants: one is the time delay between release of a pollutant and the appearance of harmful effects; the second is the geographical distance between the place of pollutant discharge and the site of harmful effects. Both the time delay and the geographical distance are often substantial, so that even when control measures are adopted, widespread and increasing damage may still be done by earlier pollutant releases. In other words, if we wait for experience to show us the limits of tolerance for pollutants, it may be impossible to prevent those limits from being substantially exceeded as a result of past action.
Up to this point in the study, The Limits of Growth is descriptive, assembling known information about population, industrial output, food supply, non-renewable resources, and pollution. The relationships among these five components are many and varied, and it is a mark of the boldness and assurance of the authors that they have ventured to quantify and model them to an extent that permits a look at the world of the future on a variety of assumptions.
Some examples of the relationships are:
- Life expectancy in a population increases as the nutritional level of the population increases, in a curvilinear relation that is steep at first and flattens out as high nutritional levels are reached.
- Resource usage per capita increases as the level of industrial output per capita increases. The United States has reached a point where the curve has flattened as more and more income is spent on services, which consume fewer resources. The world as a whole, however, is at a point where the curve is rising more and more steeply as industrial output increases.
- Birthrates decline as gross national product per capita increases, with a time lag. The mechanism seems to operate through a decline in the desired family size and an increase in the availability and effectiveness of birth control methods.
- Increases in pollution reduce life expectancy, to a minor extent at first but to a major extent when pollution is multiplied, say, eighty or a hundred times present levels.
Taking more or less historical values for these and a vast number of other relationships and projecting them into the future, the world model shows a growth in food per capita and industrial output per capita until about the year 2000. At that time, continuing growth in the population and a rapidly diminishing resource base force a sharp decline in food and industrial output per capita. Pollution increases for some further time, and population does not peak until about the mid-21st century. By the end of that century, the population is back down to a level similar to that of the end of the 20th century, but only 10% or so of the resource base is left, industrial output per capita is back to, say, 19th-century levels, food per capita is half that of the year 1900, and pollution is no longer a problem. Basically, the world collapse in this picture is the result of resource exhaustion despite an assumption that world reserves are 250 times 1970 consumption.
Suppose new discoveries and new technology double the effective quantity of resources. With this change, the world model’s picture is not much improved. Resources last a little longer, but increased usage for a few more years depletes them almost as far by the end of the 21st century as in the prior example. Pollution, however, with the increased industrialization, becomes a major factor in the first half of the 21st century. This, along with a decline in food production, leads to population growth and decline very much as before.
A number of readers of The Limits of Growth have felt that it underestimates the possibilities of technological advancement. After all, it has been pointed out, a scientist in 1872 could easily have proved that a city the size of London in 1972 would be impossible because of the problems of stabling the horses needed for transportation and disposing of the manure to avoid asphyxiation. The study does, however, acknowledge technology, and the third run of the world model assumes that technology, through the use of nuclear energy for recycling and for new processes of extraction and use, as well as through the elimination of dependence on fossil fuels, creates a situation of virtually “unlimited” resources. It turns out, however, that the result is much like the preceding ones. The villain is pollution, reaching great heights early in the 21st century as a result of the increased industrialization made possible by the greater availability of resources.
Having identified the significance of pollution in the model, the next step is to assume that technology not only creates the “unlimited” resource situation but also reduces pollution per unit of industrial and agricultural output to one-fourth their 1970 values. The resulting fourth run of the world model still shows the 21st century ending with a collapse in population and industrial output, though pollution seems to be under control. The villain this time is food production, limited largely by the quantity of arable land. Despite high inputs of capital and resources to agriculture, to the point of substantial diversions from industrial output, rising population outstrips the ability of the Earth to produce food, and collapse of the system follows.
With perhaps increasing desperation, the world modelers tried improving on the last situation, first by assuming a doubling of the agricultural yield of land, second by assuming the introduction of “perfect” birth control methods — for those who want to use them — and third, by combining the last two assumptions. This last scenario credits technology with the resource utilization and pollution control improvements mentioned before, as well as increased land productivity and effective birth control methods. This seems to achieve a constant population in the first half of the 21st century with a very high standard of living, but land and resource depletion take over, food per capita declines, and the century ends in the by-now familiar collapse, with pollution ascending and population dwindling.
At this point, the study, not surprisingly, reaches a conclusion:
“The basic behavior mode of the world system is exponential growth of population and capital, followed by collapse.”
The collapse is the consequence of time lags in the interrelations among elements of the system, which permit some of them, such as population, to “overshoot” the sustainable limits, with the result that deficiencies in other elements, such as food, become accentuated and the whole system deteriorates. Having shown that technology is not the answer, The Limits of Growth next makes a frontal attack on growth by assuming, first, a stabilization of population in some manner — the difficulties are recognized — through making births exactly equal to deaths and, second, a stabilization of industrial capital so that new investment exactly equals depreciation for the same period. If both of these stabilizations, population in 1975 and capital in 1985, are added to the model but the technological advances are left out, the result is still unsatisfactory because of resource depletion and a declining standard of living.
Only by assuming a combination of stabilizing policies and technological advances does it seem possible to achieve an equilibrium position through the 21st century. With a suitable set of assumptions, a computer run of the world model shows a stable population a little larger than today, food per capita twice the present world average, an industrial output per capita several times today’s world average but only half the present U.S. average, and minimal pollution. This is the best the Club of Rome studies have to offer: a no-growth world as far as population and industrial capital are concerned; a level of nourishment about equal to that of the U.S. today; a worldwide material standard of living at one-half of today’s U.S. level; all made possible only by the enforcement of a number of major governmental controls. While a large majority of the world’s present population would have good reason to embrace such a future, the U.S. and other well-off parts of the world would not be likely to do so, unless — and this is a fundamental point of the whole study — the alternatives are worse.
To demonstrate how limited the alternatives are, the final run of the world model shows that waiting until the year 2000 to introduce stabilizing policies will not produce an equilibrium. By that time, it appears that the population will already have grown, and resources will have been so depleted that ultimate collapse cannot be avoided.
What is the untutored but interested citizen to make of this somewhat eminently sponsored, computerized, well-graphed, and diagrammed study? The result is dramatic enough, but it is presented almost in a manner of understatement, which tends to add credibility to its conclusions. The Economist, however, in forthright manner, says that “The report represents the highwater mark of old-fashioned nonsense…” Carl Kayser accuses the authors of crying “Wolf” and complains that the study effort could have been better directed toward the threat of nuclear war or the maldistribution of wealth among nations.
Certainly, however, the central idea of the study is significant. In a finite world, exponential growth cannot go on indefinitely. Furthermore, with pressures that double in 33 years, the time between half gone and all gone is only 33 years, a very brief span in which to change the values and institutions of men. The treatment of technology, however, is not satisfactory. Starting with a sort of frozen technology as the base case, the world model attempts to make up for the deficiency by some specific technological assumptions for supplemental runs. None of these assumptions is the equivalent of an exponentially growing technology, for which there is substantial evidence if we just think back on how the material world has changed at an accelerating pace during our own lifetimes. A growing technological capability can continue to push the limits of our resources far beyond the maxima postulated by the world model.
Furthermore, in some respects, the Earth is not finite. The sun continuously pours upon the Earth a vast amount of energy. Some tiny part of this energy we manage to capture when we build a hydroelectric plant to use the energy of falling water, which arrives at our reservoirs only because the sun’s heat previously raised it as water vapor into the skies. Some of the sun’s energy has been trapped in the past by the process of photosynthesis so that the resulting fossil fuels are, in fact, fossilized solar energy. It would seem quite possible to learn to use the sun’s energy more directly before catastrophe arrives. It is significant that any waste heat resulting from using solar energy would presumably be no more than would have been added to Earth by the natural incidence of the energy falling on the Earth as it inevitably would have. In other words, there would be no ultimate waste heat pollution problem from solar energy, unlike other sources.
Nuclear fission and fusion also represent virtually unlimited sources of energy. Granted, technology has a considerable way to go for efficient development, but the potential clearly seems to be there.
Between solar and nuclear sources, it would appear that worries over the shortage of fossil fuels can, in the long run, be forgotten. Also, these two sources should have minimal pollution effects.
In the additional time which technology should give us, the population problem may yield to changed world attitudes. We have recently learned that fertility rates in the United States have dropped to the zero-growth level of 2.1 children per woman. Population would still grow for about 65 years because females coming of age will enlarge the child-bearing potential for some time to come, but even further declines in the fertility rate are not out of the question. There are reports that the birth rate has dropped markedly in China, and this, of course, can materially affect predictions for the future.
The large role given to pollution in the world model is difficult to understand. Technology is assumed, in some of the runs, to reduce the rate of industrial pollution by three-fourths. The United States is on a course that surely will do far better than that. The costs are high, and we will be doing without other things in order to pay for the avoidance of pollution, but it does seem to be a problem for which the social, political, and economic controls will be sufficient, and for which the technology will be forthcoming.
In short, the major defect of The Limits of Growth is that it underestimates technology. Its demonstration that one-shot massive applications of technology will not spare us from calamity is unconvincing when we look at ongoing technological progress. In this light, it seems reasonable to expect that in the long run, energy will not be a finite resource, and that the limitations we now see in fuel supplies will not be a constraint on growth. Also, enough progress is already being made in controlling pollution to justify the conclusion that the world systems will not be subjected to collapse from this cause.
Indeed, despite the problems of delayed response, the possibility of collapse seems exaggerated. Familiar economic, social, and political mechanisms should operate to slow exponential growth very materially if world limits are approached. It is not at all clear that the world model adequately incorporates the action of prices in directing the course of economic activity. Social responses and political actions are already having an effect on growth rates. Granted that these mechanisms operate more slowly than many would like, they do provide a powerful countervailing force.
The Limits of Growth does explore serious problems and does help to make us aware of interrelationships that exclude simplistic solutions. Its significant contribution to today’s thinking is to establish the need for an attack on the whole, employing all of the skills of mankind — technical, social, and political — to aim for a world that increasingly fulfills the desires of every inhabitant of this planet for material and spiritual well-being. Whatever the deficiencies of this report may be, we have no excuse for not pursuing the matter, both by study and by action.
Frederick T. Searls
Chit-Chat Club, San Francisco
December 11, 1972