> But a terrible series of volcanos could absolutely turn Earth into a colder Venus for, say, a couple hundred years

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.