IF the planet hasn't been this warm since the 1400's, what the hell did we humans do in the 1400's to cause it then? If all of civilization went back 600 years, we'd decrease total greenhouse gass on the planet by something like 4%. So is it only our 4% that is causing all the problems, or might the other 96% that has nothing to do with humans play a part? Maybe climate change is a (gasp) "NATURAL" phenominon.