I think both of those posts pro and anti CO2/global warming are about as misleading as each other. The bottom line is that none of us here know enough about radiative physics to be able to make a really informed choice - most of us will decide based on our gut sense.
CO2 is a greenhouse gas, and it's been accepted for over a century that it is a major player in heating the atmosphere. In simple terms, most of the atmosphere lets the sun and heat through to the surface, where it warms and then radiates heat back up from the surface in long wavelengths. Greenhouse gases absorb that heat, warm up and reradiate heat back to the surface. In effect, it slows the rate at which the earth cools and thereby raises the effective temperature . However, CO2 on its own doesn't have that big an effect, it's the claimed positive feedback from water vapour that causes the potential for significant warming.
The degree to which these two things combine is called the climate sensitivity, and the IPCC claim that is fairly high, while sceptics suggest the IPCC claim is exaggerated.
My view - gut sense wise - is that the sensitivity is low. I think the fact that so many of the claimed likely effects are nowhere near as severe as have been suggested, or predicted, is good observational evidence in favour of that.