The Atlantic: What Happens When the World’s Population Stops Growing?

For most of the time that humans have existed, our ranks have grown really, really slowly. There were an estimated 4 million people on Earth in 10,000 b.c., and after the following 10 millennia, the planetwide population had only reached 190 million. Even in 1800, the total number of humans was still under 1 billion. [...]

Humanity has experienced population drop-offs before—the Black Death is thought to have killed about 200 million people—but this time will be different. “In the past, when the world population experienced a decline,” Tom Vogl, a development economist at UC San Diego, told me, “it was because a lot of people died.” This coming transition, meanwhile, will be the result of people having fewer kids—a product of rising incomes and levels of education, especially for women and especially in less-wealthy countries. [...]

“When that happens on a global level, it means that that pension crisis is going to happen in many countries independently, at different points along that global path,” Vogl said. As each country encounters this problem, immigration—bringing in younger, work-ready people from countries with a lower concentration of older people—could counteract the aging dynamics. But today’s politics indicate that immigration is not a simple fix. Less controversial ways for countries to offset this problem include growing their economy (because there would be more money to go around) and creating more opportunities for women in the labor market (which would alter a country’s ratio of workers to retirees). [...]

When Eloundou-Enyegue thinks about the coming demographic shifts, he also wonders how they will alter the world’s cultural centers of gravity. “Because the young shape a lot of the large segments of the culture—let’s say, artistic culture, or sports culture—it would be interesting to see where most of the young people [will be],” he says. According to his calculations based on the UN’s data, the proportion of all humans on Earth under the age of 25 who live in Asia will drop from 56 to 37 percent between next year and 2100. Meanwhile, Africa’s share of the global population of young people will shoot up, from 25 to 48 percent. (The proportion living in the rest of the world will not fluctuate much.)

read the article