as per the theory of co2 precipitating the Permian extinction, i am aware of some very recent research that makes the claim that the extinction entirely happened during an 80,000 year ice age on the border of the Permian and Triassic periods. (https://www.sciencedaily.com/releases/2017/03/170306091927.h...)
if the data are correct, it seems pretty convincing to me that it wasn't the warming that caused that extinction.
btw, your point about the planet not being destroyed is well taken. i guess what i'm trying to understand is how the positive feedback loop of temp->co2->temp is broken if trace amounts of co2 is such a massive forcing. when the earth had 4000+ ppm of co2 in the atmosphere, there had to be some other, much stronger, forcing to bring the temperature back down.