Capitalism's modus operandi is to produce and sell an ever expanding supply of goods and services for ever greater profits. But the earth is finite. So is its ability to absorb wastes and toxins. While food yields shrink, the world's population grows 90 million a year and the planet's life support systems move closer to catastrophe. An ever expanding capitalism and a fragile, finite ecology appear to be on a calamitous collision course.

Resources are always limited. It’s just about how judiciously you use them. Use them smartly, and in the best way possible, where they will have the greatest impact.

After basic needs are met, higher incomes produce gains in happiness only up to a point, beyond which further increases in consumption do not enhance a sense of well-being. The cumulative impact of surging per capita consumption, rapid population growth, human dominance of every ecological system, and the forcing of pervasive biological changes worldwide has created the very real possibility, according to twenty-two prominent biologists and ecologists in a 2012 study in Nature, that we may soon reach a dangerous “planetary scale ‘tipping point.’ ” According to one of the coauthors, James H. Brown, “We’ve created this enormous bubble of population and economy. If you try to get the good data and do the arithmetic, it’s just unsustainable. It’s either got to be deflated gently, or it’s going to burst.” In the parable of the boy who cried wolf, warnings of danger that turned out to be false bred complacency to the point where a subsequent warning of a danger that was all too real was ignored. Past warnings that humanity was about to encounter harsh limits to its ability to grow much further were often perceived as false: from Thomas Malthus’s warnings about population growth at the end of the eighteenth century to The Limits to Growth, published in 1972 by Donella Meadows, among others. We resist the notion that there might be limits to the rate of growth we are used to — in part because new technologies have so frequently enabled us to become far more efficient in producing more with less and to substitute a new resource for one in short supply. Some of the resources we depend upon the most, including topsoil (and some key elements, like phosphorus for fertilizers), however, have no substitutes and are being depleted.

…civilization’s survival dilemma in the 21st century is best described by a concept from population ecology—overshoot. This refers to the situation where a crucial resource temporarily becomes more abundant, thereby enabling a group of organisms to grow its population beyond levels that can be sustained over the long run. For a population of field mice in overshoot, the critical resource might consist of small plants whose unusually robust growth has been triggered by high levels of rainfall. For humanity currently, the critical resource is fossil energy. Temporary energy abundance has led to many good things (for some of us, anyway): more food, more people, more commercial products, more knowledge, more comfort, and more convenience. But we are about to become victims of our own success.

The problem with basing your entire economy and raison d’être on a constrained resource was that eventually you ran out of the resource in question. Decisions which had seemed canny two centuries ago during the bright days of the port’s founding and initial construction were now foolhardy in the blindingly obvious light of hindsight.

The ecological crisis, in short, is the population crisis. Cut the population by 90% and there aren't enough people left to do a great deal of ecological damage.

As long ago as 1798, Malthus explained what happens when the factors limiting the increase in any population are removed. One of the factors noticed by Darwin was that all species are capable of producing vastly greater populations than can be sustained by existing resources; populations did not increase at the rate at which they are capable was the basis for his theory of Evolution by Natural Selection.
The relevance to natural selection of this capacity for overproduction is that as each individual is slightly different to all the others it is probable that under natural conditions those individuals which happen to be best adapted to the prevailing circumstances have a better chance of survival. Well, so what? Well, take a look at the figures for the human population of this world. One hundred fifty years ago it stood at about 1,000 million or in common parlance today, 1 billion. It then took about a 100 years to double to 2 billion. It took 30 years to add the third billion and 15 years to reach today's total of 4.4 billion. With a present world average rate of growth of 1.8%, the total population by the year 2000 will have increased to an estimated 6 billion and in that and in subsequent years 100 million people will be added to the world population each year. In fact it could be as much as 16 billion by 2045. As a consequence the demand on resources of land alone will mean a third less farm land available and the destruction of half of the present area of productive tropical forest. Bearing in mind the constant reduction of non-renewable resources, there is a strong possibility of growing scarcity and reduction of standards. More people consume more resources. It is as simple as that; and transferring resources and standards from the richer to the poorer countries can only have a marginal effect in the face of this massive increase in the world population.
The object of the WWF is to "conserve" the system as a whole; not to prevent the killing of individual animals. Those who are concerned about their conservation of nature accept that all species are prey to some other species. They accept that most species produce a surplus that is capable of being culled without in any way threatening the survival of the species as a whole.

The idea that we can just keep growing forever on a finite planet is totally imbecilic.... Julian Simon, a professor of junkmail marketing, and his kind, think technology will solve everything.... We can use up the Earth then we can just jump into spaceships and fly somewhere else.... Technology does nothing to solve problems of biodiversity or living space or arable cropland.... Fresh water and arable cropland are finite resources.... We are already far beyond what we can support sustainably.... The provincial view you get from someone living in some wealthy American East Coast city is wildly different from reality. Most of the world is tropical, hungry and poor. Visit the developing world and southern hemisphere and you get a very different view of reality.

...the Earth in general can only support so much animal life, and for every aditional pound of human beings and his animal favorites, a pound of other animal life must disappear.

I don't claim to have any special interest in natural history, but as a boy I was made aware of the annual fluctuations in the number of game animals and the need to adjust the "cull" to the size of the surplus population.
It took about three and a half billion years for life on earth to reach the state of complexity and diversity that our ancestors knew as recently as 200 years ago. It has only taken industrial and scientific man those 200 years to put at risk the whole of the world's natural system. It has been estimated that by the year 2000, some 300,000 species of plants and animals will have become extinct, and that the natural economy, upon which all life depends, will have been seriously disrupted.
The paradox is that this will have been achieved with the best possible intentions. The human population must be properly fed, human life must be preserved and human existence must be made safer and more comfortable. All these things are obviously highly desirable, but if their achievement means putting the survival of future generations at risk, then there is a pressing obligation on present generations to apply some measure of self-restraint.
What has been described as the «balance of nature» is simply nature's system of self-limitation. Fertility and breeding success create the surpluses after allowing for the replacement of the losses. Predation, climatic variation, disease, starvation--and in the case of the inappropriately named Homo sapiens, wars and terrorism--are the principal means by which population numbers are kept under some sort of control.
Viewed dispassionately, it must be obvious that the world's human population has grown to such a size that it is threatening its own habitat; and it has already succeeded in causing the extinction of large numbers of wild plant and animal species. Some have simply been killed off. Others have quietly disappeared, as their habitats have been taken over or disturbed by human activities.

We live in an age dominated by the problem of limits. We are witnessing the end of progress. We have reached the saturation point. Are we going beyond these limits? Are we going to take the risk? There is much work to do to maintain the planet.

To be sure, the human individual can, even must, feel and know himself to be limited—and this is what distinguishes him from the animal—but he can become conscious of his limits, his finite-ness, only because he can make the perfection and infinity of his species the object either of his feeling, conscience, or thought. But if his limitations appear to him as emanating from the species, this can only be due to his delusion that he is identical with the species, a delusion intimately linked with the individual’s love of ease, lethargy, vanity, and selfishness; for a limit which I know to be mine alone, humiliates, shames, and disquiets me. Hence, in order to free myself of this feeling of shame, this uneasiness, I make the limits of my individuality the limits of man’s being itself. What is incomprehensible to me is incomprehensible to others; why should this worry me at all? It is not due to any fault of mine or of my understanding: the cause lies in the understanding of the species itself. But it is a folly, a ludicrous and frivolous folly to designate that which constitutes the nature of man and the absolute nature of the individual, the essence of the species, as finite and limited.

I mean, you can pretend up to a certain point that the world has infinite resources and that it's an infinite wastebasket-but at some point you're going to run into the reality, which is that that isn't true.

There is presumably an upper limit to the carrying capacity of humans on earth—of the numbers that agriculture can support—and that number is usually estimated at between 13-15 billion, though some people think the ultimate numbers might be much higher. (2001)