the earth has been way, way hotter than it is right now
i'm not saying greenhouse gases have no effect, but this isnt unprecedented on earth by any means
It has not been that much hotter than it is. Right now we are on the hot side as far as long term temperatures go. I don't know where you get this "way, way" stuff from. Anyway, here's the famous CO2/Temperature graph, someone has to post it first, might as well be me: