The March 3rd edition of The New Yorker had a long article (it was the only thing I got read this AM during my usual Saturday AM breakfast out) about the global declining birth rate. The whole thing reads like science fiction, not unlike Children of Men.
https://www.newyorker.com/magazine/2025/03/03/the-population-implosion
The poster child for this issue is South Korea (half of whose population lives in Seoul, BTW), whose birth rate stands at 0.7. (2.1 is considered a "replacement rate"). Each successive generation is a fraction of the size of the previous one. There are schools in the country that had one thousand students at their peak that now have five.
The U.S. rate isn't nearly that low: 1.66, but still well below replacement. But even immigration won't address the issue of who is going to do the work and pay the taxes that fund Social Security, since for the U.S. the nations from which people immigrate also have declining birth rates.
Reasons? Lots of them. But a big part was the deliberate planning on the parts of non-governmental organizations and governments who panicked about population growth, the food supply, and the environment decades ago. If you think about it, NGOs and governments have, at best, very coarse control over the "birth rate" knob, so getting it tuned perfectly to the desired rate - whatever that may be - is almost impossible. Most got it too low. South Korea got it way too low.
I won't live long enough to have to worry much about this. But eventually we'll have to use AI and automation just to do fundamental stuff like farming and distribute basic goods; there won't be anyone to do the work, and the people that do exist will be too old.
This won't really effect the climate change issue, since climate change is happening on the span of decades, while population decline is on the span of generations.
It occurred to me that this would be an interesting SF story: aliens - perhaps "obligate reproducers" (adults have to procreate or they die) - show up and say "Hey, no sweat, we're patient, we'll stick around until you aren't using your planet anymore. It's just a matter of time."
Edit: capitalism seems to depend on an ever growing population of consumers. What it really means when the population explosion trend reverses - as inevitable as this may seem - is anyone's guess... but it can't be good.
