A density of population such that the available resources of an area are unable to support the resident people; contrasted with underpopulation, where the area is able to support a greater density. It is impossible to derive a precise figure for overpopulation, as the concept is subjective and rarely related to any agreed minimum standard of living. It is important to take account of the area under consideration. For example, the crude population density of Chad is only 7 people per km²/19 per sq mi (2003), yet the country could be regarded as overpopulated because the harsh physical conditions mean that the land is unable to support that density. The daily (197880) per capita calorific intake was 1808, which is 76% of the United Nations Food and Agricultural Organization recommended minimum requirement.
Overpopulation is the condition of any organism's numbers exceeding the carrying capacity of its ecological niche. In common parlance, the term usually refers to the relationship between the human population and its environment, the Earth.
Introduction
In the context of human societies, overpopulation occurs when the population density is so great as to actually cause an impaired quality of life, serious environmental degradation, or long-term shortages of essential goods and services. It is rather a situation of shortage of resources that must be caused by population and not by other factors.
Overpopulation can result from increases in births, a decline in mortality rates, which is linked to increases in life expectancy, or from an unsustainable use and depletion of resources.
Resources to be taken into account when evaluating when an ecological niche is overpopulated include clean water and air, food, shelter, warmth, or other issues related to survival. The Water Crisis arguably manifests the most fundamental resource limitation for the human population.
Malthus' theory
Thomas Malthus argued in An Essay on the Principle of Population, first published in 1798, that if left unrestricted, human populations would continue to grow until they would become too large to be supported by the food grown on available agricultural land, by the middle of the 19th century. He proposed that, while resources tend to grow linearly, population grows exponentially. At that point, the population would be restrained through mass famine and starvation. Malthus argued for population control, through "moral restraint", to avoid this happening. As the population of a species exceeds the amount of available resources, it decreases, sometimes sharply, since the lack of resources causes mortality (deaths) to increase. This process keeps the population in check and ensures it doesn't exceed the amount of resources.
Over the two hundred years which followed, famine has overtaken numerous individual regions; proponents of this theory state that these famines were examples of Malthusian catastrophes, though they invariably have occurred because of sudden drops in production, not increases in population. On a global scale, however, food production has grown faster than population. It has often been argued that future pressures on food production, combined with threats to other aspects of the earth's habitat such as global warming, make overpopulation a still more serious threat in the future. Among the best-known example of such an argument is The Limits to Growth, a report produced for the Club of Rome in the early 1970s, and The Population Bomb, in the same era, whose predictions were based on static analysis.
Population as a function of food availability
Some recent research and experiments question the contemporary belief that human populations are a naturally explosive independent variable. Thinkers such as David Pimentel, a professor from Cornell University, Virginia Abernethy, Alan Thornhill, Russell Hopffenberg and author Daniel Quinn propose that like other animals, human populations predictably grow and shrink according to their available food supply – populations grow in an abundance of food, and shrink in times of scarcity.
Proponents of this theory indicate that every time food production is intensified to feed a growing population, the population responds by increasing even more. Some human populations throughout history support this theory, as consistent population growth began with the Neolithic Revolution, followed by subsequent agricultural revolutions, and thus food supply began consistently increasing and continues to do so in the present. This can be observed in cultural contexts, as populations of hunter-gatherers fluctuate in accordance with the amount of available food and are significantly smaller than populations of agriculturalists, who increase the amount of food available by putting more land under agriculture.
Critics of this idea point out that birth rates are lowest in developed nations, which also have the highest access to food. In fact, some developed countries have both a diminishing population and an abundant food supply. The United Nations projects that the population of 51 countries or areas, including Germany, Italy, Japan and most of the successor States of the former Soviet Union, is expected to be lower in 2050 than in 2005.
Food production has outpaced population growth, meaning that there is now more food available per person than ever before in history (although as with other resources this is distributed very unevenly;
The demographic transition
The theory of demographic transition holds that within a generation after the standard of living and life expectancy increases, family sizes start dropping.
Today about half the world lives in nations with sub-replacement fertility.
Another version of demographic transition is that of Virginia Abernethy in Population Politics, in which she claims that the demographic transition is primarily in effect for nations where women enjoy a special status (see Fertility-opportunity theory). In strongly patriarchal nations, where she claims women enjoy few special rights, a high standard of living tends to result in population growth.
Her theory runs counter to some of the available empirical evidence. For example Iran had a Total Fertility Rate of 1.82 children per couple in 2005, which is below the replacement rate of 2.1 to 2.3 children per couple needed to maintain population. Iran is widely perceived as a patriarchal nation, and yet any population growth that occurred there came not from increased birth rates, but from decreased mortality rates, i.e.
"Demographic entrapment" is a concept developed by Maurice King that has not gained widespread acceptance. Many sub-Saharan countries are quoted as examples of demographic entrapment, for example Uganda, where the total fertility rate stands at 6.71 children born per woman, even though the economy has shown steady growth since 1990 and life expectancy stands at 53 (figures from the 2006 edition of the CIA world factbook). Other African countries, such as Zimbabwe, have seen their population growth slow down, but not stop, on account of a decrease in life expectancy and an increase in emigration, with the birth rate remaining high: the democratic transition in reverse.
Viewpoints on population growth
Optimists believe that the 2006 population level of over six billion may be supported by current resources, or that the global population may grow to ten billion and still be within the Earth's carrying capacity. In The Skeptical Environmentalist, Bjørn Lomborg argues that, because of the falling rate of population growth in most parts of the world and because of new science and technologies, there is little problem with overpopulation.
Critics may argue that poor people can't afford advanced technologies. The percentage of the world's population living on less than $1 day per day has halved in twenty years. The number of people in poverty though has increased as population's have grown.
Optimists may also point out that meat production is very energy inefficient, so that food availability would increase if protein sources like soybeans were used in lieu of meat, since humans would then be eating lower on the food chain.
Optimists claim that there will be no mass starvation due to a shortage of arable land. Hydroponics in autonomous building gardens and greenhouses grow more food in less space, although the requirement for fresh water (itself a scarce resource) limits this technology. Hydroponics and food from bacteria and fungi, like Quorn, may allow the growing of food without having to consider land quality, climate, or even available sunlight, although such a process may be very energy-intensive.
Some claim that not all arable land will remain productive if used for agriculture, as they argue that some marginal land can only be made to produce food by unsustainable practices like slash-and-burn agriculture. One measure of the world's current overpopulation is established by a non-profit research group, which calculates for each year the date on which the present population has used up the Earth's resources for the present year on a sustainable basis.
Optimists have also been criticized for failing to account for future shortages in fossil fuels, currently used for fertilizer and transportation for modern agriculture.
There are a variety of viewpoints as to when the Earth's carrying capacity was exceeded.
Population projections
The world's human population has quadrupled in the course of the last hundred years.
The United Nations states that
Almost all growth will take place in the less developed regions, where today’s 5.3 billion population of underdeveloped countries is expected to swell to 7.8 billion in 2050. By contrast, the population of the more developed regions will remain mostly unchanged, at 1.2 billion. Worldwide population is currently growing by more than 75 million people per year. During 2005-2050, eight countries are expected to account for half of the world’s projected population increase: India, Pakistan, Nigeria, Democratic Republic of the Congo, Bangladesh, Uganda, United States of America, Ethiopia, and China, listed according to the size of their contribution to population growth. The population of 51 countries or areas, including Germany, Italy, Japan and most of the successor States of the former Soviet Union, is expected to be lower in 2050 than in 2005. Because deaths are projected to exceed births in the more developed regions by 73 million during 2005-2050, population growth in those regions will largely be due to international migration. In 2000-2005, net migration in 28 countries either prevented population decline or doubled at least the contribution of natural increase (births minus deaths) to population growth.Another United Nations report projects that world population will peak at 9.2 billion around 2075 .
The already mentioned David Pimentel claims that population outcomes for the 22nd century range from 2 billion people (characterised as thriving in harmony with the environment), to 12 billion people (characterised as miserable and suffering difficult lives with limited resources and widespread famine).
The book The little green handbook reasons that in 2050 about 7.7 billion people would be expected to suffer from illness, lack of adequate sanitation, hunger, and extreme poverty, provided that the high population estimates of year 2050 are realised.
Some countries currently have growth rates of over four percent. By 2050, it is estimated that
India will displace China from first place with a population of about 1,550,000,000
Effects of overpopulation
Some problems associated with or exacerbated by human overpopulation:
Inadequate fresh water for drinking water use as well as sewage treatment and effluent discharge Depletion of natural resources, especially fossil fuels Increased levels of air pollution, water pollution, soil contamination and noise pollution Deforestation and loss of ecosystems that sustain global atmospheric oxygen and carbon dioxide balance; rickets) Poverty coupled with inflation in some regions and a resulting low level of capital formation Low birth weight due to the inability of mothers to get enough resources to sustain a baby from fertilization to birth Low life expectancy in countries with fastest growing populations Unhygienic living conditions for many based upon water resource depletion, discharge of raw sewage and solid waste disposal High rate of unemployment in urban areas (leading to social problems) Elevated crime rate due to drug cartels and increased theft by people stealing resources to survive Conflict over scarce resources and crowding, leading to increased levels of warfare Over-utilization of infrastructure, such as mass transit, highways, and public health systems Higher land pricesExtra-terrestrial population projections
Even as far back as 1798, Thomas Malthus stated in An Essay on the Principle of Population:
"The germs of existence contained in this spot of earth, with ample food, and ample room to expand in, would fill millions of worlds in the course of a few thousand years."
Gerard O'Neill has suggested that, by taking the completion of his proposed Island One as year zero, maximum population growth could then result in a population of 7.3 billion within 35 years. Space advocates and others have made various projections regarding future human population growth in outer space. Marshall Savage (1992, 1994) has projected a population of five quintillion throughout the solar system by 3000, with the majority in the asteroid belt.
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Many authors (eg. Clarke, Isaac Asimov) have argued that shipping the excess population into space is no solution to human overpopulation, saying that (Clarke, 1999) "the population battle must be fought or won here on Earth." It is not the lack of resources in space that they see as the problem (as books such as Mining the sky demonstrate);
Overpopulation as a theme in fiction
In 1729, Jonathan Swift wrote the satirical essay A Modest Proposal where he suggests one solution for both the problem of overpopulation and the growing numbers of undernourished people in Ireland can be solved by the raising of infants as food.
Science fiction writers have frequently made famous predictions in which they portrayed dystopian futures in which the world has become massively overpopulated. The 1960s saw increasing anxiety about the prospect of the exponential growth of world population, underscored by the publication of Paul R. Ehrlich's non-fiction The Population Bomb, in 1968. The 1969 Star Trek: The Original Series episode entitled The Mark of Gideon dealt with a race of overpopulated aliens who abducted Captain Kirk to solve their population problem.
In the same year, John Brunner's science-fictional Stand on Zanzibar was published. Nolan and George Clayton Johnson (1967), describing a dystopian future society in which the population is kept young by euthanizing everyone who reaches a certain age, thus neatly avoiding the problem of overpopulation. A 1972 film called Z.P.G. featured an overpopulated, very polluted future Earth, whose world government practices Zero Population Growth, executing persons who violate the 30-year ban on procreation.
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From the 1980s, there has been an evident lessening of such fears in science fiction.
One of the reasons for this may be the rise of environmental fiction with The End of Nature (1990) by Bill McKibben, the environmental trilogy Ishmael (1992), The Story of B (1996), and My Ishmael (1997) by Daniel Quinn. Virgin, Environmental Change and Human Health in Countries of Africa, the Caribbean and the Pacific, Stockholm Environment Institute, Stockholm, Sweden (1999) ^ ^ American Council for the United Nations University (2002) ^ Heidelberger Institut fur International Konfliktforschung, Konfliktbarometer 2003: 12. ISBN 0-201-47959-1
Authors
alphabetized by last name
Virginia Abernethy professor (emerita) of psychiatry and anthropology, Population Politics, (1993) Albert Bartlett emeritus Professor of Physics, Arithmetic, Population, and Energy: The Forgotten Fundamentals of the Energy Crisis, (1978) Joel E. Ehrlich Bing Professor of Population Studies, The Population Bomb, (1968) The Population Explosion, (1990) The Population Bomb, (1995) reprint Garrett Hardin 1941 Stanford University - Ph.D. Microbiology Living Within Limits, (1995) reprint" Bjørn Lomborg Master's in political science at the University of Aarhus in 1991, The Skeptical Environmentalist: Measuring the Real State of the World, (2001) Andrew Mason Professor, head of the University of Hawaii's population studies program, Population change and economic development in East Asia: Challenges met, opportunities seized (2001) Donella Meadows, lead author Ph.D. in biophysics from Harvard, Jorgen Randers, professor of policy analysis at the Norwegian School of Management, Dennis Meadows, director of the Institute for Policy and Social Science Research Limits to Growth: The 30-Year Update (Paperback) (2004) Thomas Malthus English demographer and political economist, An Essay on the Principle of Population, (1798) Julian Lincoln Simon Professor of Business Administration The Ultimate Resource 2, (1998)" Ben J.
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