I’ve read a bit on the topic too and I think I agree? One of the other obvious occurrences we’re living through is some form of population collapse. Although it’s termed “collapse” I think it’s better conveyed as “global population shrink”. As far as sustainability, I think we can all wait for generational turn over and see what shakes out. But that brings with it other problems like not having enough younger people to care for the elderly or meaningfully contribute to a tax revenue. Anyway, glad you pointed that out. In a cacophony of doom from main stream media (news, social, political, celebrities) maybe this isn’t one of the very big problems that needs global attention right now.

Not just tax and elder care. If you have fewer young people than old then when those young people take the place of their older colleagues in their various professions you wind up losing a lot of tacit knowledge. If there are 1.5 olds for every young then that young one needs to learn 150% of the skills and knowledge that they did before. In such cases the extra information often gets lost. This is how population collapse leads to civilizational collapse.

Climate impact is roughly O(N) for the number of humans. Sure, some have more impact than others but reduce humans and reduce impact.

This is kind of defeats the point of environmentalism. The point is for humans to live on a sustainable planet, not for us to accept artificial death.

> The earth is not overpopulated nor in danger of being so.

Depends how you look at it; from a "how much food can we grow" perspective, it's possible to put up hydroponics etc. everywhere (with enough effort) and feed a trillion.

Conversely, if you want to "solve" climate change with a reduced population (rather than rolling out new tech) the maximum sustainable number of humans is about 8 million at today's per-capita average emissions level.

"Maximum" is all about the tech and what it can let us do.