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Original citation: Pimentel, David & Marcia Pimentel. "Feeding the world's population." BioScience 50:5 (May 2000). 387.

Feeding the World's Population

If the current rate of growth is sustained, the world's population will double, from 6 billion to 12 billion, in approximately 50 years. Even if a policy of 2.1 children per couple, instead of the current rate of nearly 3 children per couple, could be adopted tomorrow, the world's population would continue to grow for approximately 70 years before stabilizing at nearly 12 billion. This "population momentum," attributable to the current young-age distribution, is responsible for the continued population growth in most countries. Clearly, national populations with a median population age of only 16 years will continue to grow over the full 70 years.

More people will require more food, more water, more shelter, and more jobs. A recent report from the World Health Organization signaled the seriousness of the human population explosion: more than 3 billion people -- half the worlds population -- are malnourished. Never before have so many, or such a large proportion, of the world's people been malnourished. Malnourishment does far more than make it difficult for people to work or enjoy their daily lives; it is a serious ailment that increases a person's susceptibility to life-threatening diseases such as malaria, diarrhea, and AIDS.

Per capita shortages of basic food resources are responsible for much of this malnutrition. Poverty, as well as inadequate or unfair distribution of food supplies, also con tributes. The most consequential of the causes of malnourishment, however, may well be the expansion of the human population's houses, roads, and industries over more and more agricultural land. In addition to lost cropland, these changes compromise pure water and other vital resources essential for productive agriculture.

More than 99% of human food comes from the land. For example, cereals are the mainstay of human diets worldwide, constituting 80 -- 90% of the world food supply. Although cereal grain harvests per hectare have increased slightly since 1984, these harvests have had to be divided among more and more people, thus lessening the per capita availability of grains. Food availability per capita, as measured by cereals, has been declining since 1984.

Food production should be increasing dramatically to meet the needs of a rapidly expanding population, yet available world cropland per capita has declined 20% during the past decade. Each year erosion by wind and water destroys more than 10 mil lion hectares of cropland. And erosion is intensifying worldwide, especially in developing countries where overgrazing is common and the rural poor remove crop residues for fuel for cooking. Valuable forests also are being removed. Irrigation is essential to agricultural productivity in arid areas, but irrigated cropland per capita has declined approximately 10% during the past decade. The decline is attributable in part to problems with salinization and waterlogging, although in some regions farmers simply can not afford to irrigate.

Despite all the projections about human population growth, no one really knows exactly how large the human population will be 50 years from now. We do know, how ever, that the more than 6 billion people alive now are already stressing the earth's land, water, and biological resources, as well as polluting the environment.

To improve the growing imbalance between population numbers and food supply, humans should actively conserve cropland, fresh water, energy, and biological resources. Populations in developed countries could contribute by reducing their high consumption of resources. The development of appropriate, safe technologies holds the promise of improving food production.

As the human population increases, the right to freedom from malnourishment, hunger, poverty, and diseases is gradually eroded. Freedom to enjoy open space and treasured natural environments also is infringed. If we are not brave enough to limit our numbers, nature will impose its own limits upon us.

-- David Pimentel
Marcia Pimentel
Cornell University