There would be some increase in mortality among remote tribes as radioactive fallout from a large scale nuclear war drifted down globally, but that wouldn't be enough to cause human extinction.
Good luck getting them to adopt your useless ass in the post-apocalypse.
https://en.wikipedia.org/wiki/Permian–Triassic_extinction_ev...
This is a good point, but the event wouldn't need to be more volcanic so much as that volcanism would need to ignite more carbon-containing materials - naively I would expect there to me more "fuel" in the Earth than there was 300m years ago.
Minoans went from the thriving trading center of the Mediterranean with written language as old as Egyptian Hieroglyphics to seemingly irrelevant for a while during the Bronze Age because volcanic eruptions seemed to have turned the air they breathed to poison. Not to mention places allegedly hit by the fall of volcanic ash whose remains are so far deep we only speculate they lived there.
I’m really hoping this is a ironic literary reference to “How I learned to stop worrying and love the bomb”
Climate change won't cut it, neither would total nuclear war.
Even if you had something like an impact big enough to superheat the entire atmosphere, enough humans might survive inside buildings, basements, subways, etc to carry on.
Modern civilization though is a lot more fragile. It's possible to blast us back to pre-industrial times and the easy to access resources are mostly gone. It's not clear that we could bootstrap a second industrial revolution easily.