Adobe Stock
Declining birthrates may not trigger the same alarms as war, pandemics, or climate disaster — but they could prove just as consequential, according to economists Dean Spears and Michael Geruso.
In a July 27 Wall Street Journal column, journalist Greg Ip explores the pair’s new book, After the Spike: Population, Progress, and the Case for People, which calls for urgent attention to the risks of global depopulation.
Spears and Geruso, both affiliated with the University of Texas at Austin, argue that global population decline poses a deeper threat than many realize. As Ip wrote, their message is not just about economic fallout, but about “a more fundamental proposition: More people is a good thing in and of itself.”
According to projections referenced by Ip, if global fertility were to fall to the US level of 1.6, the world’s population would peak at 10.2 billion in 2080 before beginning a long-term decline.
“It will not fall to 6 billion or 4 billion or 2 billion and hold there,” Spears and Geruso write. “Humanity could hasten its own extinction if birth rates stay too low for a long time.”
Ip clarified that Spears and Geruso do not predict literal extinction. Rather, he says, they emphasize that compared to a stable population, depopulation carries serious drawbacks — economic, social, and philosophical.
In describing the broader cultural context, Ip points out that past fears of overpopulation, such as those made famous in Paul Ehrlich’s The Population Bomb, still shape attitudes today. While most demographers now dismiss such alarmism, Ip noted that some progressives still associate population growth with environmental harm.
But Spears and Geruso challenge that view directly. As Ip summarized, they argue that “humans, through ingenuity and behavioral change, have reduced pollution and expanded available resources as their numbers grew.”
For example, they point to China, where, despite an increase of 50 million people over the past decade, particulate air pollution has been cut in half.
They also argue that larger populations increase the odds of innovation. Ip explains their logic: If a fixed share of the population becomes scientists or entrepreneurs, more people means more ideas.
“Developing a vaccine or a smartphone costs the same whether for one person or 8 billion,” Ip noted. “The bigger the population, the more such investments become financially feasible.”
Ip said that their most striking claim may be philosophical rather than economic.
“It’s better if there is more good in the world,” Spears and Geruso wrote. “That includes good lives: it’s better if there are more good lives.”
Unlike many on the political right who focus on native birthrates and immigration restrictions, Spears and Geruso frame their concern as global and humanist.
“We want to convince our fellow liberals and progressives that… other people’s lives aren’t just good for those people, but for them, too,” Geruso said in an interview.
Spears and Geruso don’t propose a definitive fix for declining birthrates, but they aim to shift how the issue is understood and discussed.
“The first step in solving a problem is to acknowledge the problem. Right now, falling fertility isn’t broadly seen as a problem,” Ip concluded. “There are no randomized control trials to determine what raises fertility, as there are for maternal health or childhood nutrition. Spears hopes their book will ‘invite people to pause there for a second and not welcome depopulation by default, but ask the question, would stabilization be better?’”
