Where the heck is an option for agnostics!? I don't believe in global warming, its not that sort of a thing. I don't know if its happening either, I am not a climate scientist. If id have to put down my foot somewhere, id say that the climate is probably warming, but I wouldn't draw any conclusions from it just yet. We have been measuring temperatures on our planet directly for totally insignificant time. So I'm agnostic. Polluting less is good regardless of the reasons why its done. So is reducing human footprint and developing a sustaining way to live because if its not sustainable there will be wars and famines and general mess to live through. If some people need a scary global warming monster standing behind their backs to strive for cleaner world, so be it. I don't. Oh, and man made is also natural causes. Men, us, in our existence are entirely natural. Us going extinct like the dinosaurs is also natural ;) Us surviving as we are is unnatural, so much so that its nearly impossible. We either evolve, transform and conquer the space or die. I guess that's what happens to most life in this universe.