Does carbon dioxide cause warming? This is one basic process of greenhouse gases and warming. If carbon dioxide does not cause warming, then it cannot be forcing temperatures. To answer this, we have to look at basic radiative physics. Absorption curves for major greenhouse gases have been well established for some time. For example, see the curves published Howard, 1959 and Goody and Robinson, 1951:
Using Planck's equation to overlay the amount of incoming solar radiation to outgoing thermal radiation, and you can see that the top of the outgoing thermal radiation curve aligns nicely with the carbon dioxide curve - this means that incoming light goes through the carbon dioxide but is absorbed going out.
So yes, basic radiative physics shows that carbon dioxide does cause warming.