Monday, September 18, 2023

When will the earth's population peak, and what happens then?

Dean Spears, The World’s Population May Peak in Your Lifetime. What Happens Next?, NYTimes.

Most people now live in countries where two or fewer children are born for every two adults. If all people in the United States today lived through their reproductive years and had babies at an average pace, then it would add up to about 1.66 births per woman. In Europe, that number is 1.5; in East Asia, 1.2; in Latin America, 1.9. Any worldwide average of fewer than two children per two adults means our population shrinks and in the long run each new generation is smaller than the one before. If the world’s fertility rate were the same as in the United States today, then the global population would fall from a peak of around 10 billion to less than two billion about 300 years later, over perhaps 10 generations. And if family sizes remained small, we would continue declining.

What would happen as a consequence?

Next:

Sustained below-replacement fertility will mean tens of billions of lives not lived over the next few centuries — many lives that could have been wonderful for the people who would have lived them and by your standards, too.

Perhaps that loss doesn’t trouble you. It would be tempting to welcome depopulation as a boon to the environment. But the pace of depopulation will be too slow for our most pressing problems. It will not replace the need for urgent action on climate, land use, biodiversity, pollution and other environmental challenges. If the population hits around 10 billion people in the 2080s and then begins to decline, it might still exceed today’s eight billion after 2100. Population decline would come quickly, measured in generations, and yet arrive far too slowly to be more than a sideshow in the effort to save the planet. Work to decarbonize our economies and reform our land use and food systems must accelerate in this decade and the next, not start in the next century.

This isn’t a call to immediately remake our societies and economies in the service of birthrates. It’s a call to start conversations now, so that our response to low birthrates is a decision that is made with the best ideas from all of us.

Long-run population decline?

n fact, in none of the countries where lifelong fertility rates have fallen well below two have they ever returned above it. Depopulation could continue, generation after generation, as long as people look around and decide that small families work best for them, some having no children, some having three or four and many having one or two.

Nor can humanity count on any one region or subgroup to buoy us all over the long run. Birthrates are falling in sub-Saharan Africa, the region with the current highest average rates, as education and economic opportunities continue to improve. Israel is an example of a rich country that, as of today, has above-replacement fertility rates. But there, too, fertility rates have been falling over the decades, from 4.5 in 1950 to 3.0 today. Israel may not be above 2.1 for many more generations.

Living in a "smaller" world ((much)lower population)?

There are many ways to live a life or be a family, and having that freedom and diversity is good. If an inclusive, compassionate response to population decline emerges someday, it need not be in conflict with those values. If one in every four pairs of American adults would choose to have one more child, that would be enough to stabilize the U.S. population. In that future, there would still be many ways to live a life or be a family; two kids on average doesn’t mean two kids for everyone.

Nobody yet knows what to do about global depopulation. But it wasn’t long ago that nobody knew what to do about climate change. These shared challenges have much in common, which gives humanity some shared experience to build on.

There's much more at the link.

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