The Tragedy of the Commons

Concern for the environment goes back hundreds of years, but mistreatment of natural resources became a big cause midway through the 20th century. Huge industrial complexes spilled their effluence into the environment as worldwide population exploded and consumer demands skyrocketed. A deadly smog killed thousands of Londoners in 1952; Rachel Carson’s 1962 book Silent Spring catalogued the fatal chemicals being released into the air and water; Cleveland’s Cuyahoga River, bright yellow with pollution, caught fire in 1969. Something had to be done.

In 1968, Garrett Hardin gave a lecture, later published as an article in the magazine Science, asserting that the main cause of environmental danger comes from the burgeoning size of the human population. His essay, “The Tragedy of the Commons,” pointed out that a single person can kill an animal or dump garbage onto a wilderness, and that act won’t have much effect, but when populations increase and millions of people do so, the ecosystems involved become stressed to the breaking point.

Hardin’s 1968 lecture borrows a concept first presented in 1833 by mathematician and economic theorist William Forster Lloyd, who explained that an unregulated resource opened for common use, such as a grazing area, would quickly be overrun as more and more people take advantage of the resource. With the skyrocketing growth of the world’s human population, more of these “commons”—air, water, weather, ocean fisheries, forests, mines, and grazing lands of all types—are stretched to the breaking point by pollution and overuse. Hardin’s lecture title, “The Tragedy of the Commons,” has since become the name for this phenomenon.

In 1970, the US Environmental Protection Agency was established, and the first Earth Day was observed; in 1971, Greenpeace came into existence; in 1972, the US Clean Water Act became law. Since then, environmentalism has grown more important in the public eye. More recently, concerns about climate change—caused by CO2 emissions from cars, factories, power plants, and other sources—have inspired campaigns to achieve carbon neutrality in human activity.

Every attempt to reduce pollution is blunted, though, by the growing human population. Each year, the population grows a small amount. While this fact alone doesn’t seem alarming, over many decades, such growth accumulates in the same way that a small interest rate on a bank account leads, over a few dozen years, to huge growth in the size of the account.

As an ecologist, Hardin’s chief concern was worldwide overpopulation, which he believed would eventually overwhelm humanity’s ability to provide for itself as it pushed ecosystems past their capacities. Since Hardin published his lecture, the world’s human population has more than doubled. Such growth undercuts efforts to clean up environments: If, for example, a society halves its pollution rate per person but doubles its population, the net environmental benefit is zero.

In 1798, economist and clergyman Thomas Malthus predicted that agricultural growth would increase world populations “geometrically” until they outstrip people’s ability to feed themselves, causing widespread famine. Malthus’s population prediction has proven correct, as the number of humans since his day has grown faster and faster, especially during the 20th century. Hardin warns that this will, eventually, cause a disaster.

Such catastrophes already have occurred many times in human history. Environmental mismanagement led to the demise of the Mayan, Greenland Viking, Pueblo Anasazi, Easter Island, and Khmer Empire societies, among others (Jared Diamond’s book Collapse describes these and other examples of environmental disasters that destroyed civilizations. Study guides for that book and for Rachel Carson’s Silent Spring are available at SuperSummary).

In modern, industrialized nations, however, population growth has, in recent decades, drifted downward to the point where many countries’ populations have begun to drop. This is mainly because of an unexpected effect of modern life: Raising children has become more expensive.

For 10,000 years, humanity had an agrarian lifestyle—most people lived and worked on farms—and children were economically valuable because they helped their families manage crops and livestock. A family needed to raise several offspring, partly for the added help around the farm and partly because most kids died within a few years of birth. Then the Industrial Revolution ushered in an urban lifestyle, and today most people in the world live in cities and work in factories or offices. Most children no longer milk cows and pitch hay, and, given the dangers of machinery, they aren’t permitted in most work settings. Instead, they attend school to learn the basics of the complex, literate work most adults must perform.

Children still need food, clothing, and shelter, which cost money—and a lot of it. The US government in 2020 estimated that the inflation-adjusted average cost to raise an American child from birth to age 18 is $284,570 (Fersch, Patricia. “What Does It Cost to Raise a Child?“ Forbes, 30 Dec. 2020). Children thus have shifted economically from valuable farm labor to expensive urban liabilities.

Meanwhile, thanks to modern medicine and public health, most kids survive to adulthood. As of the early 21st century, in Western-industrial nations, the average couple today raises slightly less than two offspring; over time, this leads to a drop in total population. The change from high to low birthrates is known in the social sciences as the “demographic shift” or “demographic transition,” which—in industrialized nations, at least—presents an escape route from unbridled population growth.

Technological growth, contrary to Malthus’s fears, turns out to be exponential: Instead of steadily increasing supplies chasing skyrocketing human population growth, resource management has improved at a rate that has begun to surpass even the exponential growth of humanity. Food supplies thus generally have kept up with the population. Still, Malthus’s doomsday scenario of starving billions may yet come to pass if the environment were suddenly to collapse under the weight of an already huge population that continues to overuse resources.

Not all countries have yet developed Westernized industrial economies, though most seem intent on doing so. In the meantime, those nations, their people largely agrarian, retain strong incentives to produce many children. These countries continue to add to their numbers, and though the world’s rate of population growth has slowed by half since Hardin’s lecture, total numbers may peak at around 10 billion during the 21st century. The resulting environmental stressors keep growing as well.

The world’s largest population is in China, which introduced laws in 1980 that prohibited more than one child per couple, with the result that tens of millions of female fetuses may have been aborted or baby girls killed after birth because Chinese culture strongly prioritized male heirs. This shows that coercive laws can have unexpected effects, not all of them good. China in 2015 rescinded the one-child law and faces its own demographic shift from high to low birthrates.

Hardin’s arguments address the threat to humanity from environmental catastrophe; later ecologists also pointed to the tragic losses that the plant and animal kingdoms would suffer because of human encroachment. In the past few decades mass extinction of species has begun, prompting a movement to rename the current geological age as the “Anthropocene epoch” for the massive changes to the planet’s surface and lifeforms caused by human activity. This concept adds to the moral argument for regulating population, and it doesn’t detract from the original idea about looming civilizational collapse, but people are naturally more responsive to threats to themselves than they are to risks faced by other creatures.

Of those environmental threats, a warming climate may be the gravest, but any number of other environmental stressors might also touch off a catastrophe. Whether technological improvements can combine with demographic shifts in time to save humanity remains to be seen. It’s likely that the outcome will be determined during the 21st century.

The jury is still out on Hardin’s predictions, but he raised crucial concerns. Frustrating humanity’s best efforts, the population continues to grow, and the environmental effects continue to stress ecosystems. Hardin predicted that technological solutions might fail, and, despite a massive and impressive cleanup of an importantly symbolic ecosystem, in 2020 the Cuyahoga River caught fire again.