Humanity is going to shrink
No one has any idea how to stop the decline, so we need to prepare for the consequences.
The problem with population growth projections is that they naturally follow an exponential curve. When “like begets like” — when the number of kids is just proportional to how many people are currently alive to have kids — you get a function that either explodes to infinity or decays to zero as time goes on. So no matter what the fertility rate is, humanity is always on course for either runaway overpopulation or an empty planet…if you project far enough into the future. Exponentials are inherently unstable.
That said, the farther the total fertility rate gets from the “replacement level” of about 2.1 live births per woman, the sooner the big population changes will occur. And lots of countries that demographers had previously predicted to stabilize somewhere close to the replacement rate are starting to drift toward seriously low birth rates.
For example, China. With 1.4 billion people, China accounts for 17.5% of the global population. For years the government claimed that fertility was around 1.7, but those numbers were probably being faked. Not only was the true number lower, but it’s fallen precipitously in recent years. Right now it’s around 1.09, which is among the lowest in the world.
Or take the U.S. For years, our fertility rates seemed to defy gravity, hovering at or even slightly above the replacement rate, and prompting lots of triumphalist long-term projections. But much of this was due to high teen pregnancy rates and the high fertility rates of recent immigrants, which both diminished in the 2010s. Our TFR stood at 1.66 in 2021 according to the UN (though some sources have us a bit higher). The number of babies born in 2022 was 15% below the number born in 2007.
Finally, there’s Africa. With a total fertility rate of 4.3, it’s the one continent that’s still above replacement. But it’s headed in the same direction as everyone else. Here’s a graph for Africa as a whole, and the 8 most populous countries:
Other sources have these countries at even lower rates, and the other sources may be right. As a recent Economist article noted, every time demographers go take careful measurements in big African countries like Nigeria, they’re surprised on the downside. Africa’s population is still going to rise a lot thanks to population momentum, but hopes that it would defy the general trend toward childlessness appear increasingly far-fetched.
The whole world is heading toward negative population growth. Immigration can help specific countries (especially the U.S.) maintain their populations for a while at the expense of others, but as the whole world converts to small families, even that stopgap solution will become less feasible.
This doesn’t mean that the human race will inevitably shrink to a small dying remnant of childless old people, huddling together for one last bit of companionship as nature or our AI descendants take over the planet. That scenario is science fiction, since it requires projecting very very far into the future. But the global fertility collapse will have big enough implications in the short term that it’s worth preparing for.
So let’s talk about some of the effects of our low-fertility future, and then afterwards we can talk about how we might change things in the long term to avoid those scary sci-fi scenarios.
A shrinking world is a world of toil
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