Worst case is that we hit a feedback loop after at +5C and spike to +10C or more and we get a repeat of the Permian extinction. No responsible scientist can co

Worst case is that we hit a feedback loop after at +5C and spike to +10C or more and we get a repeat of the Permian extinction. No responsible scientist can come out and predict this because it is unknown territory. But if you want to go to Mars based on a meteor-driven event at the P-T transition, you damn well better worry that we recreating the events that lead to the 'Great Dying' at the end of the Permian that took out 90% of all _species_ at the time.