Let me make a small addition to the previous post. There is little, if any, debate about the rising CO2 concentration. Questions on which there is much less agreeement are: 1) what portion of that increase is due to [excessive] activites of humans; 2) what part of the rise is simply a the result from increasing temperature due to natural climate change; and 3) how much of the temperature increase could be due to the rise in CO2 concentration.