Whatever you choose to call it, it's a problem when there is too much of it and it's trapping heat. The CO2 in the atmosphere has gone up by about a third in just the last 100 years. When man causes something to change on the planet that much, it seems a good idea to figure out the consequences. It's like saying water isn't harmful. But if you drink enough of it, you can die from it.
In point of fact there is no crisis,
The fact that burning carbon is warming the planet and causing potentially disastrous and irreversible change is the reason. Climate scientists the world over are in almost total agreement on that. Of course people like Rush will just continue to refuse to look at the science and instead rely on things like CO2 is not a pollutant, plants use it, the Earth is too large for man to be able to affect it, etc. I choose science.