Earths history has had many extraordinary climate changes, we already know of events like Permian–Triassic extinction.
I appreciate many people feel an obligation for humanity to minimise its effect on climate change, but the way I see it, change is constant. If we don’t cause an extinction event, earth will do it just fine without us.
The best result for humanity is if we get off this rock asap and improve our technology. The quicker we do this the better. If we have to ruin earth and its beautiful climate in the process, so be it.