No, you missed the point, the CLIMATE IS ALWAYS CHANGEING. It is never ever static.
Thus the comment, what the weather is today, is just transitory. It wouldn't remin the same 100 years from now, if men had never climbed out of the trees...
Living in harmony means what? For every action man takes, whether intentional or not... it effects everything else. I suppose you want man to go back to being more like the Native Americans who were in touch with Nature then? (I hate to break this to you, but they abused the land, the wildlife.. burned whole forests.. to suit thier needs)
http://www.eugenicsarchive.org/eugenics/ Click the Eugenics Popularization, read the flahs bit, it's... enlightening.