...CO2 is
just the principal greenhouse gas in the earth atmosphere...
http://en.wikipedia.org/wiki/Carbon_dioxide
http://gristmill.grist.org/story/2006/12/22/224450/84
And as already tried to explain (but with little success I think) greenhouse effect *does* cool down the temperatures when year after year cold fresh air melting on the poles go to interfere and slow down important currents like the the north atlantic one (for diminished salinity of the ocean and counter-currents).
http://en.wikipedia.org/wiki/Gulf_Stream
PS. Also, some temporary cool down is scientifically irrelevant and not contrary to the theory: -
http://gristmill.grist.org/story/2006/11/9/182921/777
PPS Oh about your last link. Nice finding of external source on the Wiki. But let's have fun and read the sentence that leads to it:
While individual scientists have voiced disagreement with these findings, (and here is your link!) the overwhelming majority of scientists working on climate change agree with the IPCC's main conclusions.(two links here showing the majority, and many others here: http://gristmill.grist.org/story/2006/11/11/23656/027 and here http://gristmill.grist.org/story/2006/11/13/221250/49)