...you say that "the atmosphere and climate of this planet has been an ever-changing process since the beginning of time, sometimes in rapid drastic ways and at other times slowly over eons." you have to remember that almost all of those "drastic changes" have come with nearly world wide extinction.
I'm not really sure what your point is... I also said, "Untold numbers of plants and animals have come and gone with these changes." But again, what is your point? If the climate is changing by natural processes of time, what can we do about it? The answer is nothing! There has never been a total extinction event, something has always survived to carry on. Usually it's the most specialized life forms that are made extinct... those that can survive on diverse food sources, and in diverse habitats are the most likely to survive. Mankind is the most diverse life form this planet has ever produced... we live on near every non-liquid surface and eat literally millions of different foods... mankind is the most likely to survive an extinction event.