I agree with you pire.

What has been known is that if you have more carbondioxide in a glass house you feel hoter than outside (Carbon dioxide traps the infrared radiation responsible for heating).

Yes, scientists have tried to correlate increase of CO2 concentration vs. the increase in temperature of the earth. And they say that there is a similar trend (it is there in IPCC, 2007 report). In my understanding also it might be the carbon dioxide increasing the global warming (because of the similar trend), but there might be other effects (may be effects from sun itself ).