My view - I think we are all fooling ourselves really if we want to try do something to change the situation.
Sure we may have a small effect, but do you really think for example that the human race can stop the next ice-age etc., things that have been happening on earth for millions of years.
Us humans are merely a blip on evolutionary time scale and given a few more million years, as a race we probably won't be around anymore anyway.
Millions of species have appeared and disappeared over the course of time, and we are just another species subject to the whims of the universe so what does it matter if we die out as a race within the next 200 years or next 20 000 or 2000 000. What effect do we really have on the universe itself. Nothing.....We are insignificant.
So enjoy life while you can. If it makes you feel better then do your bit, but it won't make any difference in the long run.
*now I will go hide away*