I wanted to imply that some places wouldn’t be reduced to Renaissance levels of technological advancement. There’s a middle ground between things being fine and a year zero event.

Edit: Like the examples I gave earlier of Australia and Indonesia will be literally uninhabitable by humans. I don’t see how places that are still habitable lose all their progress and become like Mad Max. Or at least I don’t think that necessarily follows as a logical conclusion from the fact that global warming is happening.

Edit 2: A global year zero event is one of the possible outcomes but I don’t think it’s the most likely one. There’s always a temptation for people to want to imagine that they are “the last generation”, you see it throughout history. This temptation seems to come from people having a hard time conceiving of society progressing after they have died. It’s like an egotistical impulse to believe that the world can’t continue after you die.