Opinion | A birthrate bomb? A quiz on world population and what it means for the future. (2024)

For centuries, the United States and other nations have relied on rising populations to sustain their vitality. Along with improved productivity, an expanding labor supply drives long-term economic growth. So, what does the generational math look like now?

The key number is “the replacement rate,” at which a population remains stable between generations. Generally, this is around 2.1 children per woman. The United States had long outperformed other industrialized nations: As recently as 2008, it hovered around the replacement threshold. No longer. In 2023, the U.S. fertility rate fell to a record low of 1.62.

The United States is still better off than China, whose birth rate was once 7 births per woman. Now it stands at just 1.1, placing it near the bottom globally. What do these numbers mean for this U.S. rival?

Even if China’s fertility rate gradually increased to 1.48, China could “lose” close to 500 million people by 2100, according to U.N. projections.

Yet China is still emerging from its brutal “one child” policy. What about the rest of the world?

Two-thirds of the world’s population lives in countries where the birthrate has fallen below replacement level. The E.U.’s fertility rate stands at 1.46. Russia’s is 1.5. India, home to 1.4 billion, dropped below 2.1 for the first time in 2020. But East Asia has seen the sharpest declines. In 1960, South Korea’s fertility rate was around 6 children per woman. Today, it is the lowest in the world at 0.78.

There are exceptions to the rule of global population decline. They are just concentrated in one region. Population projections suggest that 8 in 10 people will live in Africa and Asia by 2100. Afghanistan is also an outlier. Conflict-ridden societies tend to have higher birthrates. Stable countries — particularly after sustained periods of economic growth — tend to revert toward the replacement rate. Then, eventually, they shrink.

These facts suggest that lower birthrates should not be wholly unwelcome. They reflect shifts toward delayed marriage, fewer teen births, less unintended pregnancy, lower child mortality and smaller families, which are the product of higher living standards, mass education and female workforce participation. Governments should not seek to reverse this progress, but to limit the trade-offs these positive trends bring.

In that, the United States has an underappreciated advantage: immigration. The U.S. population would begin shrinking, too, if it weren’t for the too-often-derided inflow of new people. But even at current immigration levels, the U.S. population is projected to peak in 2080 and then begin declining. In a low-immigration scenario, the population could peak as early as 2043. Unlike China, a closed society in which acquiring citizenship is close to impossible, the United States can significantly increase immigration levels to stave off population declines in coming decades.

Even assuming that political opposition to high levels of immigration could be overcome, a welcoming policy would still likely fail to prevent U.S. population decline indefinitely; as countries get richer, quality of life improves and birthrates decrease in even more places.

The U.S. government could try to make it easier for people to have the number of children they want. “Pro-natal” policies have mostly failed in other countries that experimented with them, however. The South Korean government spent more than $200 billion over 16 years to, in effect, pay people to have children, with little impact. Poland’s 500+ program, launched in 2016, helped increase the birthrate by 10 percent before it fell back to its previous trajectory. In the United States, demographer Lyman Stone estimates that one of the more promising pro-natal policies — a proposed 2020 bill from Sens. Michael Bennet (D-Colo.) and Mitt Romney (R-Utah) to expand child tax credits — would have increased the birthrate by a mere 0.04 children per woman at most.

Perhaps financial incentives would work better if they were much more generous. Some policies, such as better child-care assistance and poverty-fighting child tax credits, are warranted regardless of their effects on the birthrate. Yet the country already has a debt problem, and there is only so much the government can spend.

If population growth fails to pick up, boosting productivity is the other way to stave off negative economic consequences. Investing in education and workforce training could help achieve that. Innovations in artificial intelligence and other new tools could, too.

The worst option is ignoring the issue. The trends are undeniable, and the consequences of failing to adapt are as predictable as they are distressing. The world must brace itself for the reality already visible in its elementary school classrooms and maternity wards.