How Big of a Problem Is Overpopulation?

Consider the long history of overpopulation alarmism, and how the doomsayers’ fears have failed to materialize again and again. Two centuries ago, Thomas Malthus’s Essay on Population warned that out-of-control population growth would deplete resources and bring about widespread famine. His preferred solution was to decrease the birth rate by delaying marriage, but if that didn’t work he endorsed some rather extreme measures to slash the population. To prevent famine, he thought it was morally permissible to “court the return of the plague” by making the poor live in swamps and even to ban “specific remedies for ravaging diseases.” After Malthus died, the Industrial Revolution brought about unprecedented prosperity that funded the construction of safe water supplies and sewage systems at a scale never before achieved. Living standards were transformed and lifespans lengthened. As farms mechanized, food became more plentiful even as the population grew. Famine became rarer. Yet Malthus’s ideas proved enduringly popular.

By the 1970s, overpopulation hysteria came fully back into vogue. Stanford University biologist Paul Ehrlich published The Population Bomb in 1968, which opened with the lines, “The battle to feed all of humanity is over. In the 1970s hundreds of millions of people will starve to death in spite of any crash programs embarked upon now.” Shortly thereafter, in 1972, the Club of Rome issued a report called The Limits to Growth. It bolstered the old argument that population growth would deplete resources and lead to a collapse of society with evidence from computer simulations based on dubious assumptions. Those jeremiads led to human rights abuses including millions of forced sterilizations in Mexico, Bolivia, Peru, Indonesia, Bangladesh and India, as well as China’s draconian one-child (now two-child) policy. In 1975, officials sterilized 8 million men and women in India alone. Were these human rights abuses necessary? No. Instead of facing widespread starvation and resource shortages, humanity managed to make resources more plentiful by using them more efficiently, increasing the supply and developing substitutes.

Today the population is at a record high, and famines have all but vanished outside of war zones. Even in Sub Saharan Africa, the poorest area on the planet, the food supply now exceeds the recommended 2,000 calories per person per day. Yet overpopulation fears still exert a powerful hold on the public imagination. Earlier this year, a survey by Negative Population Growth found that “American high school students are very worried about overpopulation.” Many prominent environmentalists — from Johns Hopkins University bioethicist Travis Rieder to entertainer Bill Nye “The Science Guy” — support tax penalties or other state-imposed punishments for having “too many” children. Bowdoin College’s Sarah Conly published a book in 2016 through Oxford University Press advocating a “one-child” policy, claiming it is “morally permissible” for the government to limit family sizes through force to prevent overpopulation.

Even if overpopulation were to prove to be a problem, it is one with an expiration date: due to falling global birth rates, demographers estimate the world population will decrease in the long run, after peaking around the year 2070. It is now well-documented that as countries grow richer, and people escape poverty, they opt for smaller families — a phenomenon called the fertility transition. It is almost unheard of for a country to maintain a high fertility rate after it passes about $5,000 in per-person annual income. Alarmism and extreme measures to combat “overpopulation” are entirely unnecessary.