Far all we know we're the only place in the universe where complex life exists, if we die other species may still stay around to experience it.

Until they get smoked by an asteroid again. Even if nonhuman life somehow doesn’t get wiped out by other factors it’ll all die with the sun. If we are the only place where life exists then that means humanity is the only chance life has of continuing after this planet is gone.

Pretty sure humans would wipe themselves before wiping rest of the biosphere

I feel like you zoomed right past the point of having an equilibrium between population and what the planet can support

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.

This type of human-centric view is exactly why we're in this mess to begin with.

There are other species on this planet too, you know. What about them?

gotta keep it pristine for those lower organisms who will have a better shot at utopia than we ever could.

But seriously, I always see the planet as on a finite timescale anyways with the lifetime of our sun being the limiting factor (which is interesting because it's the sun that gives us all our energy for the most part ignoring nuclear). Once the sun goes kaput that's it, we better be intergalactic by then. So I wonder can we think of perhaps maximizing the number of civilizational hours spent under the sun on Earth. Is that a good framework to go by. Put another way say the sun goes out in the year 10,000, and we are to judge two scenarios

A) humans go extinct in the year 7,500 B) humans go extinct in the year 9,000

All else being equal what scenario would people prefer and why.

Our civilization doesn't have thousands of years ahead of it, unless something changes radically.

7500 - 9000 is just a wishful thinking ... we won't make it there without functioning ecosystems