[tialaramex]

Extinction isn't a mechanical consequence but a cultural one. Each generation of future humans learn that their ancestors squandered better conditions, and their offspring will definitely experience even worse conditions and they despair and have net fewer kids. We're not altering the climate for a few years, or a few decades, or even a few centuries, but more like millennia.

[senordevnyc]

I don’t think there’s any evidence that the human population will decline to anything approaching extinction levels due to people’s attitudes about the environment. To the contrary, we have the population that we have today because humans reproduce in spite of horrible conditions.