Cleaveland: How many people can Earth support?

Cleaveland: How many people can Earth support?

September 1st, 2019 by Clif Cleaveland in Opinion Columns

In 1798, Thomas Robert Malthus, an English cleric and scholar, published anonymously a pamphlet, "An Essay on the Principle of Population," in which he predicted a perpetual clash between a growing worldwide population and limited food supplies. In subsequent, book-length editions, in which he acknowledged authorship, he elaborated his ideas. He foresaw a linear rise in food production and a progressively steeper rise in population. Wars and famines might curtail population growth for short intervals. Without limits on human reproduction, mankind faced a bleak future.

In 1968, American biologist Paul Ehrlich published "The Population Bomb," a best-selling narrative which used the resources of science to analyze and to extend Malthus' theory. The message was urgent. Overpopulation would lead to calamity. Ehrlich predicted widespread famine in coming decades. Short-term increases in food production might forestall the crisis and buy time for national and international policies to bring population growth under control. Absent dramatic action, however, mankind faced deteriorating prospects.

In 1998, Ehrlich and his wife, Anne, published "Betrayal of Science and Reason: How Anti-Environmental Rhetoric Threatens Our Future" to highlight the effects of environmental degradation upon our futures. Ignorance, political opportunism, and greed undermine the resources upon which a growing population depends.

Are Malthus and Ehrlich prophets or alarmists?

In 1900, worldwide population was estimated at 1.6 billion. Fifty years later, that figure had risen to 2.56 billion, despite the carnage of two World Wars. By 2018, the estimated population had reached 7.7 billion. At current rates of growth, that number is predicted to reach 9.7 billion by 2050.

Clif Cleaveland

Clif Cleaveland

Photo by Contributed Photo /Times Free Press.

Rapid growth in population since 1950 depends upon multiple factors. Improved agricultural yields and advances in medical science, especially in the development and dispersal of vaccines against infectious diseases, have led to doubling of average life-expectancies in many countries. Once untreatable illnesses can now be cured or suppressed by a broad range of medications.

There is a less publicized downside to population growth. An estimated 11% of the world's population suffers chronic malnutrition. The World Health Organization estimates that more than three-quarters of a billion people do not have access to drinking water within a roundtrip of 30 miles. Two billion people rely upon drinking water that is contaminated with feces.

The "replacement rate of fertility" is the average number of children per female member of that society or nation that allows a population over time to remain stable. For developed countries, the replacement rate is 2.1 children per female.

The world's three most populated nations, China (1.43 billion residents), India (1.37 billion), and the U.S. (329 million) have shown steadily decreasing fertility rates — births per woman — for decades. China's annual birthrate per woman is 1.6, slightly below the U.S. rate of 1.8.

Some of the poorest nations have fertility ranging from four to eight children per woman.

For decades, U.S. foreign aid has included assistance in family planning, employing both education and technology, for those nations that desire this aid. Private foundations are active in this effort. Among the countries that have received technical assistance are Haiti, Guatemala, Honduras, Pakistan, Kenya, Liberia, and the Democratic Republic of Congo.

In early August, the Trump Administration announced plans to slash billions of dollars from foreign aid programs, including those directed at humanitarian causes. Such a move would bypass congressional authority in determining foreign assistance. These proposed cuts would disrupt assistance for family planning.

"An Essay on the Principle of Population" can be viewed either as a forecast of inevitable collapse of global civilization or a wake-up call to challenges that we must address to assure a humane future for all.

Contact Clif Cleaveland at

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