No, ancient global warming was due to all those gigantic dinousaurs, which were largely herbivores, emitting earth-shattering farts. The warming was OK by them, since they were coldblooded, but it ultimately proved to be their undoing. The asteroid set off the gas. KABOOM! That’s where precious gems come from; when the force of the exploding, methane-drenched atmosphere forced dead dinosaur carcasses deep underground, under tremendous pressure. Natural gas was trapped in those carcasses, too, which is why it stinks.
(Do I really need a < /sarc> tag, lol?)