Malthus's Essay on Population, published in 1798, still plays a role in environmental policymaking. The discrepancy between rates of human population growth and agricultural productivity lies at the heart of Malthusianism. One dynamic leads to ever-increasing population; the other to diminishing food and ecological degradation.

To avoid human suffering, Malthusians pursue worldwide zero population growth (ZPG). Because worldwide mortality levels are low, a society can attain ZPG through replacement fertility. If the average number of children born to women in a particular society equals two, then it has reached replacement fertility or ZPG. Governments today annually spend a total of $900 million to promote ZPG, mostly in less developed countries. ZPG is also the name of a nongovernmental organization that advocates for population awareness. Its origin in 1968 was inspired by Paul Ehrlich's Population Bomb.

Bibliography

Bongaarts, John. (1998). "Demographic Consequences of Declining Fertility." Science 282:419–420.

Humphrey, Craig R.; Lewis, Tammy L.; and Buttel, Frederick H. (2002). Environment, Energy, and Society: A New Synthesis. Belmont, CA: Wadsworth.

United Nations Fund for Population Action. (2000). Financial Resource Flows for Population Activities in 1999. New York.