The world is approaching a demographic turning point not seen since the bubonic plague, as plummeting fertility rates across developing nations suggest the global population could peak significantly sooner than international bodies predict.
According to a new analysis by editors at The Economist, the long-held assumption that the human population will continue to grow until the late 21st century relies on optimistic projections that may no longer hold water. While the United Nations currently projects the global population to peak at approximately 10 billion in the 2080s, current trends indicate a contraction could begin as early as mid-century.
A Global Phenomenon
For decades, falling birth rates were viewed primarily as a challenge for wealthy, industrialized nations like Japan and South Korea. However, recent data suggests this demographic contraction has gone global.
“The really interesting trend I think in recent years is the number of much lower income countries that are starting to fall below that replacement level,” said Mike Bird, Wall Street editor for The Economist.
The “replacement rate”—the average number of children women need to have to keep a population stable—is generally considered to be 2.1. While nations in East Asia have long been below this line, major developing economies are now following suit.
“You can see on the chart India there, not a rich country at all… it had a fertility rate of six 60 years ago, it’s now sub-replacement rate,” Bird noted, adding that this trend is now “true of most of South America.”
Currently, the only regions maintaining fertility rates significantly above replacement levels are Central Asia and Sub-Saharan Africa. Roughly two-thirds of the global population now lives in countries with fertility rates below 2.1.
Challenging the UN Consensus
The United Nations’ baseline projection assumes that while fertility is falling, it will eventually stabilize or even recover in nations where it has hit historic lows. Henry Curr, economics editor at The Economist, argues that these models may be overly optimistic.
“In the places where fertility has fallen really low, like South Korea, the UN assumes that fertility will pretty much immediately start recovering,” Curr explained. “It strikes me as a little bit naive.”
Curr pointed out that if current downward trends in fertility simply continue for another 15 years rather than rebounding, the peak in global population would be brought forward to roughly 2060. If the trend continues for 25 years, the peak moves even closer to the middle of the current century.
“We are going to see over the next few decades us approach this peak population position globally, which is really remarkable because the global population hasn’t fallen since the Black Death,” Curr said.
The Convergence of Class and Culture
The drivers of this decline challenge traditional sociological narratives. Throughout the 20th century, a distinct gap existed where lower-income families generally had more children than wealthier ones. That dynamic is shifting toward a global convergence.
“Historically… the norm was always that rich women had more children than poor women. You could afford the resources to have more children so you did,” Bird explained. This flipped in the 20th century, but is now flipping back. “You’ve seen a convergence across income levels, a sort of balancing out.”
In the United States, the data reveals that the decline is not driven solely by career-focused women delaying motherhood, but significantly by a reduction in unplanned pregnancies among younger demographics.
“In the US, half of the fertility decline is essentially the loss of teen pregnancies,” Curr noted. While he acknowledged this is often viewed as a “success” of social policy and education, strictly in demographic terms, it removes a significant source of population replacement.
The editors suggest that without a clear understanding of why this shift is occurring simultaneously across different cultures and economies, expecting a spontaneous reversal in fertility rates is a risky gamble. If the current trajectory holds, the era of human population growth may be drawing to a rapid close.