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When laypersons speak of overpopulation, often they are referring to exceeding the carrying capacity of the Earth. Carrying capacity is an often-used term with many definitions, a common element of which is the number of people able to sustain life within the limits of the earths environment. A definition of overpopulation should go beyond carrying capacity per se and take into account the state of the environmentwhether the condition of the natural world allows for a comfortable existence and whether the current generation will leave the Earth inhabitable for the next generation.

An issue in assessing the dynamics of overpopulation is how best to create a reliable parameter for its measurement. What level of comfort among the various alternativesthe American, the Guatemalan, the Japaneseshould be the ideal? The answer to this question determines the relevant issues of the environment to be considered and the number of people who may be sustained. Consider the amount of meat in a typical diet, the culturally defined idea of personal space, or the number of comfort goods that need to be produced and the resources involved in their production. The United States is the worlds biggest consumer of natural resources, though its population makes up only 5 percent of the worlds population. If the world were held to the American standard, the Earths carrying capacity would soon be exceeded.

The concern with overpopulation is not new. During the eighteenth century Thomas Robert Malthus declared that overpopulation was bound by nature to occur. He assumed that, if left unchecked, populations tend to increase geometrically and food and sustenance arithmetically. Malthus advised moral, that is, sexual restraint and late marriage as preventive checks to prevent population increase. He also noted that such positive checks as wars, pestilence, and famine would keep the death rate high, also resulting in a slowing down of population growth. In 1968 Paul Ehrlich made similar predictions in his popular book The Population Bomb. Unlike Malthus, he gave special attention to the degradation of the environment by humans. Ehrlichs solutions were much more dramatic. He reasoned that billions of people must starve to death for there to exist an equilibrium between population and the environment. Neo-Malthusianist concerns continued into the 1970s with the Club of Romes report on Limits to Growth and E. F. Schumachers influential 1975 book Small Is Beautiful, which spawned a counterculture with the same name. Benjamin Friedman noted in his 2005 study that portions of these themes are reflected presently in the anti-globalization movement.

Is the world overpopulated? The worlds population in the year 2006 was estimated to be over 6.5 billion strong and growing. These growth dynamics need to be considered in any discussions about overpopulation. The Population Reference Bureau projects a world population in 2050 of 9.3 billion people (Population Reference Bureau 2006). The United Nations reports that before 2050 more than 80 percent of the world will have below-replacement fertility (U.N. 2002), and their medium population projections for 2050 are very similar to the PRBs projection.

Around 3.5 billion people were added to the worlds population between 1950 and 2000; this was the fastest rate of population growth in recorded world history (UNPD 2002). By mid-century the world is expected to add another 3 billion to its population. Though the absolute number of people in the world in 2050 will have increased, its rate of growth will have slowed. There are now forty-four countries with fertility rates below the replacement level; their populations are projected to diminish in the next forty-five years. Most of the growth in the world will occur in the less developed regions of the world. Families will be smaller all over the world; indeed there has already occurred a marked decrease in average family size in most of the countries of the developing world.

If the planet is already overtaxed by 6.5 billion people, then coming decades will likely be a time of disquiet and suffering over much of the world. When considering overpopulation, one must weigh the well-being of the individual against that of all of Earths inhabitants. Rights that form the base of many nations, such as the rights to property, reproductive rights, and economic rights, will likely be less well defined in a situation where the issue of overpopulation is paramount. The right to purchase and use land may need to be regulated in order to protect the environment. Families may be forced to limit their numbers, and individuals may have to decrease their consumption to conserve natural resources and protect the environment.

It is difficult to construct the parameters of overpopulation. Considering the health of an entire world versus a single nation seems contrary to much of human history. Population projections for the rest of the century are subject to much variation depending on fertility patterns, thus further complicating the issue. As the world competes for limited resources, it is quite possible that the issue of overpopulation will be an issue of concern in many countries.

SEE ALSO Birth Control; Club of Rome; Demography; Depopulation; Limits of Growth; Malthus, Thomas Robert; Malthusian Trap; Natural Resources, Nonrenewable; Population Control; Population Growth; Population Studies


Ehrlich, Paul. 1968. The Population Bomb. New York: Ballantine Books.

Friedman, Benjamin M. 2005. The Moral Consequences of Economic Growth. New York: Knopf.

Meadows, Donella, Jørgen Randers, and Dennis L. Meadows. 2004. Limits to Growth: The 30-Year Update. White River Junction, VT: Chelsea Green Publishing Company.

Population Reference Bureau. 2006. 2006 World Population Data Sheet. Washington, DC: Population Reference Bureau.

Poston, Dudley L., Jr. 2006. Malthus, Thomas Robert. In The Cambridge Dictionary of Sociology, ed. Bryan S. Turned, 347348. Cambridge, U.K., and New York: Cambridge University Press.

Price, David. 1999. Carrying Capacity Reconsidered. Population and Environment: A Journal of Interdisciplinary Studies 21 (1): 526.

Schumacher, E. F. 1975. Small Is Beautiful: A Study of Economics As If People Mattered. New York: Harper Colophon.

United Nations. 2002. The Future of Fertility in Intermediate Fertility Countries. New York: Department of Economic and Social Affairs, Population Division, United Nations.

United Nations Population Division (UNPD). 2002. Expert Group Meeting on Completing the Fertility Transition. New York: UN Population Division Department of Economic and Social Affairs.

Chris Russell

Dudley L. Poston, Jr .


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overpopulation The situation that arises when rapid growth of a population, usually a human population, results in numbers that cannot be supported by the available resources, such as space and food. This occurs when the birth rate exceeds the death rate, or when immigration exceeds emigration, or when a combination of these factors exists. See population growth.