A classic claim from climate quacks is that, because CO2 rises lag behind temperature rises in ice core records, C02 produced by human activities can't possibly be contributing to climate change. A nice sensible explanation of why this is nonsense can be read here. But if you prefer a chuckle with your debunking, you won't find any better than this piece of pure joy from Tim Lambert's Deltoid.
CO2, warming, and causality
z, in comments:
"CO2 is not causing global warming, in fact, CO2 is lagging temperature change in all reliable datasets. "
See also my forthcoming paper: "Chickens do not lay eggs, because they have been observed to hatch from them".