Zero population growth

Zero population growth, sometimes abbreviated ZPG, is a condition of demographic balance where the number of people in a specified population neither grows nor declines, considered as a social aim [Kingsley Davis (1973) "Zero population growth: the goal and the means" in "The No-Growth Society", Mancur Olson & Hans H. Landsberg, eds. New York: Norton] .

The term is said [ [http://www.stanford.edu/dept/news/pr/97/970305davisobit.html Kingsley Davis Obituary] ] [ [http://www.britannica.com/eb/article-9029519/Kingsley-Davis Encyclopedia Britannica] ] to have been coined by American sociologist and demographer Kingsley Davis [Kingsley Davis (1967) "Science" 158, no. 3802 pages 730-739 "Population policy: Will current programs succeed?"] . It was in fact used earlier by George Stolnitz, who stated that the concept of a stationary population dated back to 1693 [George J. Stolnitz (1955) "Population Studies", Vol. 9, No. 1. pp. 24-55] . A mathematical description was given by Mirrlees [J. A. Mirrlees(1967) "The Review of Economic Studies", Vol. 34, No. 1. pages. 95-124] .

In the long term zero population growth can be achieved when the birth rate of a population equals the death rate. (This ignores migration, which is valid for the planet as whole, but not necessarily for a nation.) However, a population that has been growing in the past will have a higher proportion of young people. As it is younger people who have children there is large time lag between the point at which the birth rate falls below the death rate and the point at which the population stops rising [http://www.ditext.com/ehrlich/3.html] .

Zero population growth is often a goal of demographic planners and environmentalists who believe that reducing population growth is essential for the health of the ecosphere. However, achieving ZPG is difficult because a country's population growth is often determined by economic factors, incidence of poverty, etc.

However, even if there is zero population growth, there may be changes in demographics of great importance to economic factors, such as changes in age distribution.

ee also

*Demographic transition - Zero population growth is achieved when the birth rate of a population equals in a situation where net migration is also zero

*Z.P.G. - A science-fiction movie concerning the topic of zero population growth.

*Optimum Population Trust - A registered United Kingdom charity, think tank and campaign group

*Overpopulation- when an organism's numbers exceed the carrying capacity of its habitat.

*Zero growth

References

External links

* [http://www.wafreepress.org/55/Enviro.htm Enviro, Population Movements Merge Goals for Healthier Planet]
* [http://www.worldwatch.org/ World Watch Institute]
* [http://www.northwestwatch.org/ Northwest Environment Watch]
* [http://endofspecies.com/ The "End of species" hypothesis] Does demographic decline mark the end of humanity's life cycle? May ET civilizations follow the same path?
* [http://www.cepnet.org/ Center for Environment and Population] Science, Policy, and Public Education on Population and the Environment