How far would global births fall under persistently low fertility?
Core argument: Global annual births peaked at 146 million in 2012 and have been falling since, compared with roughly 30 million in 1700 and an estimated 18 million per year 2000 years ago, per Kaneda and Haub (2022).
At the start of Figure 1, in 1700, there were perhaps about 30 million births annually. For comparison, estimates from Kaneda and Haub (2022) indicate that there were perhaps 18 million births per year globally 2000 years ago. In 2012, at the peak, there were 146 million births worldwide. Annual births have been falling since. In the hypothetical scenario in which the world converged to an average total fertility rate of 1.5 and held at that level, then by 2300, annual global births would have fallen back down below 16 million. Thus, birth rates that are already common today in most of the world would lead to a decline in the number of global births that could be more rapid than the increase of recent centuries. Moreover, notice that the decline does not end where the graph does: As long as birth rates hold at any level below two children per two adults—even at some steady, unchanging level—the slide down would continue indefinitely. What about much more transformative changes, larger than anything yet seen. Could that avoid global depopulation? Nobody has tried anything that would adequately challenge conventions, challenge social orders, and challenge what gets society’s attention, power, and investment.

