> There is no scenario where climate change leads to human extinction

https://en.m.wikipedia.org/wiki/Clathrate_gun_hypothesis

May not be possible with modern deposits but I don’t think we are 100% sure of that, and you asked.

We could also probably burn enough carbon to send CO2 levels up where they would cause cognitive impairment to humans if we really didn’t give a damn. That would be upwards of 2000ppm. We probably have enough coal for that if we decide we don’t need Alaska. Of course that would be even more of a species level Darwin Award because we’d see that train coming for a long time.