Tacky: No one is saying that CO2 is not a harmless gas. What IS being said is that excess amounts of CO2 -- at least partially due to human activities -- in the atmosphere are adding to a greenhouse effect that is warming the planet. The "geeks" are right -- you aren't.
But just for the sake of argument let's say that the "geeks" are wrong, and there's no warming taking place. Is there any reason why you think we shouldn't reduce the human impact on our planet anyway? Do you really believe that the planet can continue to absorb all of the damage we do to it or other living beings on it? We aren't the only species on planet Earth.
As stated at the top: Your attack on "geeks" is tacky -- and without merit.