The Looming Crisis of Global Depopulation

In a recent episode of The Indicator from Planet Money, economists Dean Spears and Mike Jeruso, co-authors of the forthcoming book After the Spike: Population, Progress, and the Case for People, explore a paradoxical reality: while the global population has exploded from 2 billion to 8 billion over the last century, we are currently standing at the edge of a massive demographic shift—a looming "crash" in population numbers.

The Mechanics of Depopulation

At the heart of this issue is the "fertility rate," defined as the average number of children a woman has in her lifetime. Economists point to "two" as the "magic number" or the "replacement rate." When the global fertility rate consistently falls below this threshold, the result is "depopulation."

Spears and Jeruso note that this is not a localized phenomenon; fertility rates are declining across North America, Latin America, Europe, China, Russia, and India. The authors project that the world population will peak at approximately 10 billion around the year 2080, followed by a drastic, centuries-long decline that could see the population drop back to 2 billion.

Why More People Equals More Prosperity

Many might wonder if a smaller population is inherently better, but Spears and Jeruso argue that a larger population is a primary driver of human progress. They anchor this argument in two key economic concepts:

1. Idea Generation: Citing Nobel laureate Paul Romer, the authors emphasize that "ideas are an endlessly renewable resource." Innovation—whether in high-tech gene therapies or the organizational structure of a kindergarten classroom—relies on human collaboration. A larger, interconnected population fosters more "learning" and "sharing knowledge," which has historically "lifted all boats."
2. Fixed Costs: Many societal benefits, such as public works or medical advancements, involve high "fixed costs." The authors highlight that we have vaccines for RSV and COVID because the scale of the population justifies the investment. Conversely, there is no "vaccine for sealpox" because the affected population is too small to incentivize research. A shrinking population threatens our ability to maintain a "critical mass" of people necessary to justify investments in public goods and scientific breakthroughs.

Addressing Misconceptions: Population vs. Climate

The authors address the common counter-argument that fewer people would be better for the planet's climate. Spears argues that these are "totally separate issues." Even with current trends, the population will continue to grow for another 50 years, making it too late for population decline to serve as a primary climate solution. Instead, the focus must remain on reducing "per capita pollution" and "per capita greenhouse gas emissions" directly.

The Path Forward: Choice and Collective Responsibility

Perhaps the most striking takeaway is the authors' admission that no government has yet found a successful solution to reversing falling fertility rates. Current pro-natalist policies in various countries have largely failed to stem the tide.

Spears and Jeruso conclude that a stable future requires a society where people feel empowered to choose to have children, noting that "children are everyone's responsibility." They explicitly warn against "pro-natalism" that seeks to undermine "gender progress," arguing instead for a societal shift where parents receive the support they need. Ultimately, the authors maintain that a "big world" is beneficial for humanity, and the challenge lies in creating a social framework that values and supports the next generation without compromising the progress made in gender equality.