And they do in turn affect the ecosystem. A couple of thousand years ago Greece was covered with trees. It was a fertile and favored habitat, which incidently, fostered the western culture. Italy, indeed all of Europe and Great Britain were once heavily forested. Nothing but shadows of the former majesty and beauty.
Mankind has a propensity to pillage and waste everything it comes in contact with.
A bed partner is mother nature. As the last ice age receded, the climate naturally warmed up significantly. I haven't seen any responsible scientific data. Core samples from the two poles are starting to show cyclical patterns, but the data has not revealed man's culpability. Maybe we are nothing more than a straw in the cyclical winds of change.