Zero population growth
condition of demographic balance where population remains constant over time
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; that is, the number of births plus in-migrants equals the number of deaths plus out-migrants. The Zero Population Growth organization, founded by biologist Paul R. Ehrlich, induced a prominent political movement since the 1960s, aiming to reach zero population growth.
The movement considers zero population growth to be an objective towards which countries and the whole world should strive in the interests of accomplishing long-term optimal standards and conditions of living. It faces substantial support as well as criticism, involving different groups of people in society.
Definition
The growth rate of a human population in a given year equals the number of births minus the number of deaths plus immigration minus emigration expressed as a percentage of the population at the beginning of the given year.
For example, suppose a country begins a year with one million people and during the year experiences one hundred thousand births, eighty thousand deaths, one thousand immigrants and two hundred emigrants.
Change in population = 100,000 – 80,000 +1,000 – 200 = 20,800
Population growth rate = (20,800 ÷ 1,000,000) x 100% = 2.1%
Zero population growth for a country occurs when the sum of these four numbers – births minus deaths plus immigration minus emigration - is zero.
To illustrate, suppose a country begins the year with one million people and during the year experiences 85,000 births, 86,000 deaths, 1,500 immigrants and 500 emigrants.
Change in population = 85,000 – 86,000 + 1,500 – 500 = 0
Population growth rate = (0 ÷ 1,000,000) x 100% = 0%
For the planet Earth as a whole, zero population growth occurs when the number of births equals the number of deaths.
History
Coining the term
The American sociologist and demographer Kingsley Davis is credited for coining the term "zero population growth" (ZPG) in 1967 by discussing the negative consequences of an uncontrollably growing population and suggesting a population growth below zero as the solution across nations.
Begin with the source’s own compact description: “Zero population growth” is condition of demographic balance where population remains constant over time. The dossier treats that line as a proposition to test through Zero, population and growth, not as a finished interpretation.
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