By the End of This Century, the Global Population Will Start to Shrink

The fertility rate is falling in every country on the planet

Credit: Dong Wenjie/Moment/Getty

The great defining event of the 21st century — one of the great defining events in human history — will occur in three decades, give or take, when the global population starts to decline. Once that decline begins, it will never end. We do not face the challenge of a population bomb, so rampant in the popular imagination, but of a population bust — a relentless, generation-after-generation culling of the human herd. Nothing like this has ever happened before.

If you find this news shocking, that’s not surprising. The United Nations forecasts that our population will grow from 7 billion to 11 billion in this century before leveling off after 2100. But an increasing number of demographers around the world believe the UN estimates are far too high.

More likely, they say, the planet’s population will peak at around 9 billion sometime between 2040 and 2060 and then start to decline. By the end of this century, we could be back to where we are right now and steadily growing fewer.

“Once a woman is socialized to have an education and a career, she is socialized to have a smaller family. There’s no going back.”

Populations are already declining in about two dozen states around the world; by 2050, that number will have climbed to three dozen. Some of the richest places on earth are shedding people every year: Japan, Korea, Spain, Italy, much of Eastern Europe. “We are a dying country,” lamented Beatrice Lorenzin, Italy’s health minister, in 2015.

But this isn’t the big news. The big news is that the largest developing nations are also about to grow smaller as their own fertility rates come down. China will begin losing people in a few years. By the middle of this century, Brazil and Indonesia will follow suit. Even India, soon to become the most populous nation on earth, will see its numbers stabilize in about a generation and then start to decline. Fertility rates remain sky-high in sub-Saharan Africa and parts of the Middle East. Even here, though, things are changing as young women obtain access to education and birth control. Africa is likely to end its unchecked baby boom much sooner than the UN’s demographers think.

Why is the UN’s prediction wrong? According to Wolfgang Lutz, of the Vienna University of Economics and Business, the reason, in a word, is education. “The brain is the most important reproductive organ,” he asserts. Once a woman receives enough information and autonomy to make an informed and self-directed choice about when to have children and how many to have, she immediately has fewer of them and has them later. “Once a woman is socialized to have an education and a career, she is socialized to have a smaller family,” he explains. “There’s no going back.” Lutz and his fellow demographers at Vienna’s International Institute for Applied Systems Analysis (IIASA) believe that advancing education in developing countries, brought about by increasing urbanization, should be factored into future population projections, which the UN doesn’t do. Using those factors, the IIASA predicts a stabilizing population by midcentury, followed by a decline. Lutz believes the human population will be shrinking as early as 2060.

His is hardly a lone voice. Jørgen Randers is a Norwegian academic who co-authored The Limits to Growth, which predicted that global population would reach unsustainable levels by 2100. But since publishing the book, he has changed his mind. “The world population will never reach 9 billion people,” he now believes. “It will peak at 8 billion in 2040 and then decline.” He attributes the unexpected drop to women in developing countries moving into urban slums. “And in an urban slum, it does not make sense to have a large family.”

The Economist is also skeptical of the UN estimates: Previous projections, it observed in a 2014 analysis, failed to forecast “the spectacular declines in fertility in Bangladesh or Iran since 1980 (in both countries, from roughly six children per woman to about two now). At the moment, Africa is the source of much new population growth and the authors assume that fertility rates will continue to fall more slowly there than they did in Asia and Latin America. But no one can be sure.”