The is an old sci-fi classic, written, I think, in the late 1940's, entitled "The Earth Abides." It is still in print, and the long and short of it is, there isn't anything that man can do, that the Earth can't undo is short order.
We flatter ourselves to think that our puny machinations and attempts actually have any significant long-term impacts on the global environment.
"Earth Abides" was a great read and a lot of food for thought. The scenarios in the book aren't that off the wall at all.