Developed countries already are below reproduction rates. My country of birth is nearly at the very bottom.
You're sort of preaching to the choir here.
I firmly believe that we will be able to sequester carbon economically one day. I am not able to say when, of course. But there are a lot of ways to sequester carbon already, even though expensive ones, and I don't see why they should stay expensive forever. Humans are pretty good in applied chemistry and always come with ways to do things cheaper.
And carbon sequestration isn't something that would require consent of the entire world. Even five or six countries working together could pull it off.
We have to innovate and embrace technology otherwise other humans will do it and make our bloodlines extinct. It just sucks that doing so carries so much tail end risk and future generations have to settle that debt.
It’s so hard to predict the future though. What if what we really need is more humans to increase the probability of solving the problems that are causing the climate to change.
"Idiocracy"(2006) scenario :-)