I think we make a mistake if we allow the argument to be narrowed simply to the issue of greenhouse gases, and global warming, which is what appears to be happening again.
Obviously each of us has some impact on our surroundings, no one can deny that. If we acknowledge that every single human has an impact on his/her immediate surrounding then it becomes impossible to deny that as a whole we are impacting every place that humans are.
Again this gets into an interconnected ecosystem. Where does the smoke from our factories not pollute the air, where does the oil leakage of our vehicles and pesticides we use to keep our lawns not pollute the water, where does clear cutting a forest not decrease the number of trees to filter toxins from our air, where does the toxicity and pollution of the water not decrease the phytoplankton that produce the oxygen we need to breath?
By looking at these small things we can better understand.
If the focus is allowed to be shifted solely to the big picture it becomes much easier to deny the impact we have on the environment around us, not so if we occasionally focus on the smallest details.
Is the space that is not impacted by humans directly of a large enough scale to negate the effects we have on our collected surroundings?
I would argue it is not.
Mind you, I'm not arguing that we need to do everything that the environmentalist movement would advocate, simply stating that there is a problem, and the problem to some degree is us.
I do not for one second believe that the environmentalist movement has a monopoly on the answers, any more than I think corporations, or news departments they own, or the research papers they pay for are to be trusted to give us facts.
I think common sense would probably be the best way to go, but that is in short supply.
As an example Florida to a degree depends on tourism, many a tourist comes here with the intention of catching the
big one. How then do we justify dumping millions of gallons of phosphorous contaminated water from a fertilizer factory into the middle of the Gulf of Mexico?
Beginning the very next year we have irregular red tides of longer duration and greater frequency, which are caused by a massive bloom and resultant die off of a particular kind of algae (algae might be fed by fertilizer I think

) what do we do?
Lie and deny of course (yeah I know, circumstantial evidence and all,) say the science isn't conclusive. But then who gives a shit in the long run... So what if we have less tourists because the beaches are littered with rotting fish that were poisoned by the dead algae? BTW the decaying algae also releases a chemical into the air that makes it very hard to breath for about 1/3 of the population. Of course this would never adversely affect our economy at all.
Suddenly I want to listen to "Moon Over Marin" by the Dead Kennedys.