I don't think there are (economical) ways to stop emitting CO2 without phasing out fossil fuels. And like you said, regardless of CO2, fossil fuels will run out

I don't think there are (economical) ways to stop emitting CO2 without phasing out fossil fuels. And like you said, regardless of CO2, fossil fuels will run out anyway. I wonder if any new civilization could bootstrap off existing knowledge and artifacts about electricity. Wind and water based electricity don't require stupidly complicated tech to get going. You can probably mine copper from ruins rather than mines. Similarly, perhaps current stores of coal and oil could also support some systems for long enough? Heck, I could even imagine old oil wells to be 'easy' to re-open. In any case, neither I nor my children will be around after we destroy civilization. So I care much more about avoiding the destruction than the ability to rebuild afterwards.