CO2 is not a greenhouse gas.
Non-CO2 greenhouse gases and climate change [...] Montzka, S., Dlugokencky, E. & Butler, J. Non-CO2 greenhouse gases and climate change. [...] The influence of anthropogenic carbon dioxide emissions on climate is widely recognized, but there are plenty of greenhouse gases besides CO2 and they receive much less attention. In this Review, Stephen Montzka and co-authors summarize the current knowledge on non-CO2 greenhouse gases, including methane, nitrous oxide and halogenic compounds such as chlorofluorocarbons. Although the total warming effect of these gases is less than that of CO2, a substantial reduction in their emissions would measurably reduce the impact of human activity on our climate. And as non-CO2 greenhouse gases tend to have a shorter atmospheric lifetime than CO2, the response of the climate system to emissions cuts in the former would be faster than the response through cuts in CO2 alone.