Population growth (Encyclopedia of Environmental Issues, Revised Edition)
The world population passed the 6 billion mark in 1999, according to the U.S. Bureau of the Census, triple the 1940 population figure. By 2010 the United Nations estimated world population to be 6.8 billion, and experts predicted that some 70 to 80 million people would be added to the count every year for at least another generation. This population explosion is unprecedented in human history. The estimated population of the world in 8000 b.c.e.was about 5 million. It did not reach 500 million until around 1650, but then the rate of increase accelerated. By the mid-nineteenth century, the planet held 1 billion people; by 1975, the number was 4 billion.
Even though the fertility rate—the average number of children born per woman—declined after the late 1960’s, vigorous growth is expected to continue through the twenty-first century, and perhaps beyond. The U.S. Bureau of the Census has predicted that in 2050 the world population will be 9.34 billion. The United Nations has projected 7.8 to 21.2 billion, depending on whether the fertility rate stabilizes or increases again. Whatever the actual total, the distribution of the population will change as people migrate to urban areas, with the world’s population shifting so that, for the first time in history, more people live in cities than in rural areas. Most of the total population growth and urban growth will occur in developing countries, particularly those in Africa.
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Resources (Encyclopedia of Environmental Issues, Revised Edition)
Humans affect natural resources by displacing or consuming them. Many resources are renewable, such as forests, which can be regrown. Nevertheless, scientists fear that increased demands for such raw materials may surpass the rate of replacement. For example, increasing use of wood could cause loggers to cut down forests faster than new trees can grow; eventually, the amount of wood available would diminish. Moreover, spreading urban areas and agriculture could take over land that once supported forests.
Some resources are gone forever once used, leaving none for future consumers and necessitating replacement by other materials if the enterprises dependent on the originals are to continue. For example, if petroleum reserves are depleted, propane or natural gas might serve as replacements for heating and vehicle fuel. Not all such nonrenewable resources are replaceable, however. The biodiversity of nature is the critical example, although some commentators insist that biodiversity is not a resource for exploitation but a heritage that should be safeguarded. In any case, proponents of the preservation of biodiversity believe that the destruction of natural habitats and the attendant extinction of species obliterate much-needed new sources of food and medicines.
Species die out naturally. All the species now living on earth amount to only 2 to 4 percent of those that ever existed. Nonetheless, biologists believe that because of...
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Politics and Economics (Encyclopedia of Environmental Issues, Revised Edition)
Proposals for dealing with population growth tend to emphasize either restricted fertility or economic development, and sometimes both. Nationalism and international politics, however, complicate the establishment of policies and make implementation difficult.
Attempts to restrict fertility take various forms. A government may specify by law the number of children each couple may have. The People’s Republic of China is the best-known example of this approach: Its one-child policy, introduced in 1978, is intended to control the world’s largest national population—more than 1.3 billion in 2010. Although recognizing that China desperately needs to check growth, humanitarian groups have denounced the Chinese government for violating human rights in carrying out the policy. Most observers doubt that such a restrictive population-control policy could be effective in a country without a dominating central government like China’s.
Other nations and international organizations encourage limiting family size through two other methods. One is to teach women family-planning techniques and offer them contraceptive devices or drugs. The other is to raise the educational level of women in general to encourage women to enter the workforce. Studies in all countries show that educated, working women have fewer children on average than do uneducated women who stay at home. However, great obstacles confront such efforts....
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Philosophical Issues (Encyclopedia of Environmental Issues, Revised Edition)
Deep philosophical differences also trouble the debate on population growth. The Roman Catholic Church, for instance, treats the environment and population matters as separate issues and teaches that contraception is immoral because it is contrary to the family’s purpose to procreate. The Church vigorously objects to government interference in family life and permits birth control by rhythm method (sexual abstinence during ovulation) alone. Some radical environmentalists, by contrast, want to halt human reproduction altogether until the population returns to pre-Industrial Revolution levels or lower.
These antithetical positions reflect two fundamental questions. First, is humanity to be considered part of nature? Much Western philosophy and theology holds humanity to be superior to nature according to divine law or distinct from it because humans alone possess intelligence. On the other hand, many non-Western thinkers and environmentalists consider humanity to be an integral part of nature, or the “web of life”—in this view, species are mutually dependent on each other, and none is superior. Second, should humans take from the environment whatever they want when they want it, or should they consume only in such a way that biodiversity is not threatened?
Even if all of humankind were to agree on answers to these questions, the environment itself might settle the problem of population growth. Some...
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Further Reading (Encyclopedia of Environmental Issues, Revised Edition)
Carter, Neil. The Politics of the Environment: Ideas, Activism, Policy. 2d ed. New York: Cambridge University Press, 2007.
Cartledge, Bryan, ed. Population and the Environment. New York: Oxford University Press, 1995.
Cohen, Joel E. How Many People Can the Earth Support? New York: W. W. Norton, 1995.
De Steiguer, J. E. “Paul Ehrlich and The Population Bomb.” In The Origins of Modern Environmental Thought. Tucson: University of Arizona Press, 2006.
Hardin, Garrett. Living Within Limits: Ecology, Economics, and Population Taboos. New York: Oxford University Press, 1993.
Mazur, Laurie, ed. A Pivotal Moment: Population, Justice, and the Environmental Challenge. Washington, D.C.: Island Press, 2010.
Moffett, George D. Critical Masses: The Global Population Challenge. New York: Viking Press, 1994.
Tietenberg, Tom, and Lynne Lewis. “The Population Problem.” In Environmental and Natural Resource Economics. 8th ed. Boston: Pearson Addison-Wesley, 2009.
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Background (Encyclopedia of Global Resources)
The size of the world population is closely tied to the pace of resource use, although the impact of population growth on resource use and depletion is debated among scholars. Some scholars believe that the population of the world can continue to grow with little or no adverse impact on world resources because of technological advancement and the substitution of new resources for scarce ones. Other scholars take a more pessimistic view; some argue that, in the near future, Earth’s population will outstrip the carrying capacity of the planet for wastes and will place severe strains on certain natural resources.
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Earth’s Carrying Capacity (Encyclopedia of Global Resources)
Although estimates of the size of the world population in the past vary widely, it is estimated that the world population numbered 1.65 billion in 1900, 4.1 billion in 1975, 5.7 billion in 1995, and 6.7 in 2009. Estimates also vary widely concerning the carrying capacity of the Earth—that is, the size of the human population it can support without incurring serious, perhaps irreparable ecological damage. Several scholars have projected the human carrying capacity of the planet to be somewhere between 8 and 12 billion people; others insist that, given the standard of living in most developed nations, the carrying capacity of the Earth has already been surpassed. Beginning in 1950, the fastest growing populations have been in Africa and Asia, while the slowest rates of growth have been in some European countries. The industrial countries tend to have low rates of population growth, but they place the greatest demands on world resources.
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The Positive View (Encyclopedia of Global Resources)
Scholars such as Julian Simon have argued that a growing population is itself a resource, providing a labor supply as well as a driving force for innovation. Scholars holding this positive view of population are little concerned with the growth of population in the twenty-first century. Some argue that the rate of increase is slowing and will flatten out midway through the century. Some who hold the positive view see resource problems as generated by governmental misallocation of resources rather than by population growth.
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The Negative View (Encyclopedia of Global Resources)
The negative view of population growth enunciated, for example, by Donella H. Meadows et al. in The Limits to Growth (1972), emphasizes that continued population growth will outstrip available natural resources such as oil and some metals. In addition, the wastes generated by a growing population will be such that ecosystems will not be able to cope with the expanded waste stream, leading to increasing environmental problems. The negative view of population growth is often based on an estimated exponential growth rate for world population. Some extreme proponents of this negative view go so far as to accept natural disasters and epidemics as positive forces because they limit population.
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A Balanced Scenario (Encyclopedia of Global Resources)
There is a third view, a more balanced perspective that lies between the alarmist and Panglossian perspectives just described. The rate of world population growth has slowed, although the rate of growth is still high enough in some countries that it could double the countries’ populations within ten years. Because advances in medical technology are increasing life expectancy worldwide, there is a relationship between fertility limitation and the age of the population. A country with a high standard of living, resulting in extended life expectancy, may not be able to accept a high fertility rate in its population. Conversely, some countries have high fertility rates but a low standard of living and few elderly people because of poor medical technology. In some countries, particularly European countries, family limitation is being practiced in such rigorous fashion as to lead to a decreasing population.
The relationship between population growth, standard of living, and resource consumption is complex. The industrialized nations, which generally have low rates of population increase, usually have higher standards of living than less industrialized nations. The industrialized nations, particularly the United States, are also the major consumers of the world’s resources. Some of the world’s poorest nations, especially in Africa, have the highest rates of population increase. For example, the population of Togo is...
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Further Reading (Encyclopedia of Global Resources)
Anderson, Terry L., ed. You Have to Admit It’s Getting Better: From Economic Prosperity to Environmental Quality. Stanford, Calif.: Hoover Institution Press, Stanford University, 2004.
Brown, Lester R., Gary Gardner, and Brian Halweil. Beyond Malthus: Nineteen Dimensions of the Population Challenge. New York: W. W. Norton, 1999.
Cohen, Joel E. How Many People Can the Earth Support? New York: W. W. Norton, 1995.
Dobkowski, Michael N., and Isidor Wallimann, eds. On the Edge of Scarcity: Environment, Resources, Population, Sustainability, and Conflict. 2d ed. Syracuse, N.Y.: Syracuse University Press, 2002.
Ehrlich, Paul R., and Anne H. Ehrlich. One with Nineveh: Politics, Consumption, and the Human Future. Washington, D.C.: Island Press, 2004.
Goklany, Indur M. The Improving State of the World: Why We’re Living Longer, Healthier, More Comfortable Lives on a Cleaner Planet. Washington, D.C.: Cato Institute, 2007.
Meadows, Donella H., Dennis L. Meadors, and Jørgen Randers. Beyond the Limits: Global Collapse or a Sustainable Future. London: Earthscan, 1992.
_______. The Limits to Growth: The Thirty-Year Update. White River Junction, Vt.: Chelsea Green, 2004.
Simon, Julian L. The Ultimate Resource 2. Princeton, N.J.: Princeton University Press, 1996.
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Background (Encyclopedia of Global Warming)
The human population is a fundamental driving force of climate change. Human activities ranging from agricultural practices to the burning of fossil fuels contribute greenhouse gases (GHGs) to the atmosphere. Both the number and the behavior of human beings are basic drivers of climate change. In terms of numbers only, in the early twenty-first century, the global human population increased by about 200,000 people per day.
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History of Population Growth (Encyclopedia of Global Warming)
Hominids that painted cave walls (Homo erectus) appeared almost one million years ago. By 8000 b.c.e., modern humans (Homo sapiens) numbered around 8 million. The first 990,000 years of human existence were characterized by a very low population growth rate (15 persons per million per year). The pro-natal fertility beliefs of early humans (whether conscious, unconscious, or instinctive) were undoubtedly necessary to maintain the tenuous presence of humanity on the face of the Earth. Pro-natal fertility beliefs served humanity well for 990,000 years, which perhaps explains why they continue.
Historical estimates of the Earth’s total population are problematic. Nonetheless, there is little argument that human numbers have increased dramatically in the past three hundred years. The conventional wisdom regarding the dramatic changes in the growth rate of the human population typically attributes them to three significant epochs of human cultural evolution: the agricultural, industrial, and green revolutions.
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Agricultural, Industrial, and Green Revolutions (Encyclopedia of Global Warming)
Prior to the agricultural revolution, the human population was probably less than ten million individuals, who survived primarily by hunting and gathering. With the domestication of plant and animal species about ten thousand years ago, the human population experienced an increase in its growth rate. Jared Diamond’s book Guns, Germs, and Steel (1997) suggests that the geographic endowments of domesticable plants and animals, climate, and other environmental variables have had a profound influence on the fate of human societies, including their ability to engage in agricultural innovation. By about 5000 b.c.e., food production gains caused by the agricultural revolution enabled the planet to support about 50 million individuals.
For the next several thousand years, population continued to grow at a rate of about 0.03 percent per year. By the year 0, the population numbered about 300 million. Through the Roman Empire and the Middle Ages (0-1300 c.e.), the rate of population growth began to increase slightly because of colonization and agricultural expansion. However, there is evidence from this period to suggest that the size of the population was actively controlled by factors such as disease, famine, and war for short periods of time.
At the end of the Middle Ages, the human population numbered about 400 million. As people became more concentrated in denser urban environments,...
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Context (Encyclopedia of Global Warming)
The last few hundred years of human history was also a time of change in the human demographics. During this period, the concentration of industry in urban areas and the efficiency gains of modern agricultural machinery caused large numbers of individuals to move from rural areas to cities to find jobs. From 1900 to the present, the percentage of people living in cities went from 14 percent to about 50 percent. Demographers estimate that by the year 2025 more than 60 percent of the Earth’s human population will be living in cities. Scientists estimate that the human population will continue to increase until the year 2050, at which time it will level out at between 8 and 15 billion. In this projection, it is assumed that 90 percent of this growth will take place in the developing world.
Every human being contributes GHGs to the atmosphere because of their food, shelter, and transportation needs. Increasing human numbers means increasing GHGs in the atmosphere. As the world’s inhabitants have increased in wealth, GHG emissions have also increased. Increasing wealth historically has been related with increasing energy consumption per capita for housing, transportation, and agriculture. The significance of myriad environmental impacts associated with the size, growth, and spatial distribution of the human population should not be underestimated.
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Further Reading (Encyclopedia of Global Warming)
Diamond, Jared. Guns, Germs, and Steel: The Fate of Human Societies. New York: W. W. Norton, 1997. This Pulitzer Prize-winning book synthesizes a broad range of findings from many disciplines to paint a picture of how and why certain civilizations manifested in certain areas based on natural climatic and environmental factors.
Harrison, Paul, and Fred Pearce. AAAS Atlas of Population and Environment. Berkeley: University of California Press, 2001. Very useful for understanding the linkages between population and environment. Provides a history of human impact on the environment and discusses many of the policy responses to environmental degradation related to population and consumption.
Livi-Bacci, Massimo. A Concise History of World Population. 3d ed. Malden, Mass.: Blackwell, 2001. Excellent history of the growth of the human population in both space and time.
Weeks, John. Population: An Introduction to Concepts and Issues. Belmont, Calif.: Wadsworth Press, 1999. Introductory textbook in demography with linkages to related ideas in sociology and geography.
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Population Growth (Encyclopedia of Public Health)
Populations increase as people are born or immigrate into a country, and decrease as people die or emigrate. Rates of population growth, usually expressed as a percentage, vary greatly. In the late twentieth century, growth rates in many European nations were extremely low, and in some parts of Eastern Europe and the former Soviet Union the growth rate was negativehat is, populations were declining in number. On the other hand, in some African and Latin American nations, the growth rate was around 4 percent, which is a doubling time of less than twenty years. The United States, as of the year 2000, had a growth rate of about 1 percent per annum.
JOHN M. LAST
(SEE ALSO: Demography; Doubling Time; Population Density; Population Forecasts; Population Policies; Zero Population Growth)