Replacement fertility is around 2.10 kids per woman. Most rich countries are way below that line.

Although that leads to the mother of all natural selection - after a few generations, you'll have selected almost exclusively for families that have lots of kids. My bet is that fertility will flatten out and recover a good bit over the next few decades.

Global replacement rate is about 2.3 so ...

I wonder when many in those 'rich' countries will learn that they need to embrace that instead of 'build the wall'.

Anyway, I don't think replacement fertility is the right measure here. Replacement fertility could be crashing, but if the ratio of 'modern'* humanity is increasing as it is, then the problem remains ... there's probably a term for this if anyone knows.

* (by 'modern' [super air-quoted] I mean, those who have the wants and desires and ability to get the goods and services of the 'rich' countries).

The planet by itself can only support a few million humans. It’s human technology and intelligence that support the rest.

That is an interesting distinction, the order we bring to things--nature refined and directed. Makes me recall this analogy I remember reading years ago about a Japanese Zen garden not being something you'd experience in nature but rather only from a human tended and curated garden. That image changed the way I think about nature and humans in nature.