If someone said 'Stop Polluting the Earth' - all nations must take action! - and everyone listened and acted then perhapswe may achieve something. The two may be linked of course, but:
The earth's climate has always varied, hot to cold, ice ages to semi-tropical, seas rising then falling as more ice melts and is formed. Was that man-made over millennia or to do with the variance in sun activity?
The Chineses drew a perfect map of Greenland's coastline in the 1400s, as vq points out it was a Green Land!
The day the earth's climate stops changing is the day the earth is a dead planet.
Now - Stop Pollution! That is what we should concentrate on.