Is a Global Carrying Capacity a Myth?: Reaching the “Right” Number of People

Kristin Leitzel

Predictions of the collapse of the human species as a result of overpopulation are not new. Towards the end of the 18 th century, Thomas Malthus, an ordained minister of the Church of England, wrote his Essay on Population that claimed human populations will always push the limits of resource availability. Population growth is held in check by starvation, disease, and (he later added) delayed marriage. With humans constantly pushing the limits of the environment, we are always living at a carrying capacity. Yet Malthus wrote his essay in 1798, over 200 years ago. Today, the earth is supporting more people than Malthus could have imagined, and if starvation and disease act as checks on population, it is only on a regional level (and primarily in the least developed parts of the world). Thanks to the industrial revolution, the agricultural revolution, and several extraordinary medical advances, humans are enjoying longer and more comfortable lives. The more recent forecast of population doom, Paul Ehrlich’s Population Bomb, joined the ranks of boys that cry wolf when the Green Revolution made it possible to feed what had seemed a decade before to be an unsustainable number of people. In tech fixing our way out of probable disaster time and again, we have changed the notion of a carrying capacity from a rigid limit on the earth’s ability to support life to a flexible bound on our current technology’s capacity to sustain us.

With an expanding carrying capacity that is more a function of our current level of technology than the state of the environment, over population is viewed as a regional problem. Countries like Bangladesh and Malawi are “overpopulated” because they lack the technology of the developed world. Only in the most underdeveloped areas does the state of the environment place limits on the number of people it can support. The problem lies in the effects of overpopulation on the quality of the environment. The technology that allows us to support the level of population we have today is not sustainable, which is why we go through cycles of over extracting resources until we need to develop a new technology that either creates a new resource or makes what is left of the depleted resource last longer through increased efficiency. As Edwin Dolan writes in TANSTAFFL: The Economic Strategy for Environmental Crisis, “advances in agricultural and industrial technology have effectively increased the size of the globe… in terms of the maximum population which it will support” (58). Though relatively easy for humans, this process has not been without its growing pains for the environment.

Overpopulation, for the most part, has not caused humans much trouble. Though we are facing high levels of poverty and hunger in some areas, the overall standard of living for most of the world’s population has risen and we enjoy a comfortable if not luxurious way of life. The costs of our population have been felt by the species of animals that have been forced out of their habitat or driven to extinction and the plants that can no longer survive in the human-altered ecosystem. Areas of wilderness are shrinking as cities grow and animals have to adapt to living in close quarters with humans. Solid waste materials and air pollution concentrations are growing, which may have long-term consequences that even our innovative minds will have difficultly addressing, much less the rest of the environment. All of these problems (current and potential) have resulted in some degree from the sheer number of people that are living on the planet and are felt most strongly by non-humans. Because we do not (yet) face the environmental consequences of our numbers thanks to our technological insulation, we cannot expect our population to level off at “the population that [the world] will support without undergoing environmental deterioration.”

One possible future consequence of our population will result from overconfidence in our ability to tackle the next resource scarcity or environmental threat. Our past innovations have allowed us to continue growing our economies and our population with little change required by us. We are now at a point where over six billion people will be threatened by an environmental crisis. The layers of technological fixes that have prevented us from feeling the environmental consequences of our lifestyle are also interdependent, which means that a large-scale crisis could have a domino effect that overwhelms our infrastructure and the ability of nations to respond. This is not to say that the doomsayers are right, only that we are living in a precariously balanced static point that if tipped out of that balance could potentially lead to a collapse of our social, economic, and political systems.

Just as a fish will grow to fit the size of its tank, most living organisms grow to fit their ecosystem and exist in a state of balance. Most living organisms, however, cannot manipulate their ecosystem like humans can. Our technological advances have allowed us to build a bigger tank, but what good is a bigger tank if nothing else can live in it? The difference between humans and every other living creature is that we have the ability to increase the carrying capacity of our environment (though only for ourselves). We do not face environmental checks on our population like other species, so we continue to grow. From an anthropocentric view, there is nothing wrong with this, so long as we can support our numbers. The only check on population growth, than, is our own decision about how many people the planet can support based on what we want that planet to look like. The fact that many developed nations are experiencing declining or negative fertility rates supports the idea that people can decide to reduce our rate of reproduction. If this decision takes into account the effects of human population on the environment, our numbers may level off at a point that the environment can support without further damage to other species. In short, whether or not overpopulation will lead to the 2,000-story apartment building that covers every dry surface of the planet depends on what moral checks we place on our own population growth.


Thomas Robert Malthus,

Ehrlich, Paul, Population Bomb, pp 18-19.

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last updated 5/13/06