Humanity is about to turn a major population corner, according to a new estimate. A recent article in the Lancet predicts that by 2030, we’ll no longer be reproducing fast enough to replace ourselves.

We aren’t about to go extinct, but this is an unexpected trajectory. As recently as 2017, the United Nations predicted human numbers wouldn’t peak until 2100 when we’d reach more than 11 billion people. According to the new estimate, our numbers could rise from the current 8.1 billion to a maximum of just 9.5 billion before declining by the early 2060s.

While a catastrophic population explosion used to seem inevitable, women’s increasing levels of education and reproductive freedom have staved off some of the worst predictions of the 20th century. That’s actually something to celebrate: We’re not about to suffer a population overshoot and run out of food, as sometimes happens to animals in the wild -- and as was predicted in the 1968 book, "The Population Bomb."

But the relative number of older people will skyrocket around the world, causing anxiety among some economists, and some political leaders want more people to have more kids. On the other side, some environmentalists argue for pushing population to drop faster to slow global warming and loss of habitat for other species and ultimately for us humans. At the core of the debate are big, unanswered questions: Is 9.5 billion too many people? Will the population subsequently fall to a number that’s too low? Is there a right number of humans?

Maybe instead of focusing on the number of children people are having, policymakers should focus on the fact that too many children worldwide aren’t getting adequate nutrition, education or medical care. Even now, though humans grow enough food to feed everyone, roughly 1 person in 10 is chronically undernourished -- that’s scientific jargon for “hungry all the time” -- and more than one child in five is stunted (too short) because of chronic hunger and infections.

After all, as demographer and mathematician Joel Cohen explains, the “right number of people” question depends on yet more questions, among them: What would be the accepted standard of material wealth? How much inequality would be acceptable? Would it be okay to build cities in areas prone to catastrophic flooding and earthquakes? Do people prefer parking lots or parks?

Cohen says the new Lancet estimate is credible. “This is really the most serious piece of work in the business about what has happened and what to expect,” he said. “There are lots of connections to climate, religion, economics, politics -- but the fact is that fertility has been going down and is likely to continue to go down.”

Fertility is usually measured by looking at the number of children born each year to women of each age, from 15 to 55. But the Lancet model follows cohorts of women born each year -- counting the babies born to women who turned 15 in 1950, then 16 in 1950, and so on -- up until the time they turn 50. “Cohort fertility is a much better summary of the real experience of real women,” Cohen said. The new projection also factored in the estimated effects on education and access to contraception, both of which have a big effect on reducing fertility.

Attempts by some governments to encourage parenthood with economic incentives or abortion restrictions are failing, Cohen said. He pointed to a paper in the Journal of the American Medical Association showing that in the US, rates of voluntary sterilization rose after the Supreme Court’s Dobbs decision revoked national abortion rights. Though cause and effect aren’t proven, he said it’s possible that restrictive abortion laws are “pushing people out of reproduction … which I don’t think is the intended effect.”

It’s impossible to know all the unintended consequences of trying to engineer the population to grow, or shrink, but there’s no downside to taking better care of the children we already have.

The focus of future policy should be to help people have the number of kids they want, when they want, with whom they want. In her new book "Sex and the Planet," University of Utah bioethicist Margaret Pabst Battin starts with a thought experiment: What would happen if everyone had access to reliable, safe, free, foolproof long-term contraception, so that getting pregnant would only happen if a woman or couple opted in?

Right now, 45 percent of pregnancies worldwide (and a higher proportion in the US) are unplanned, and some of those lead to the 73 million abortions that take place every year. With reliable long-term birth control, the rates of abortion would plummet, as would the rates of teen pregnancy. Birth rates in many regions would go down, which would prevent rapid population growth. People would not need to resort to permanent sterilization.

Gloom and doom sells, of course, which is why population trends always tend to be framed as impending disasters -- whether they are baby booms or baby busts. If we can’t agree whether we’re facing too many or too few people, perhaps it’s a good time to help people have the number of children they think is right for them.

F.D. Flam

F.D. Flam is a Bloomberg Opinion columnist covering science. The views expressed here are the writer’s own. -- Ed.

(Tribune Content Agency)