mankind dominant cause of co2 says ippc, page-21

lemonwasher, nor is any mention made of water vapour, which has five to eight times the effect of CO2.

That's mainly because, for all their "science", they don't know to within 2% of atmospheric volume how much water vapour there is. Guesses vary between 2% and 4% of the atmosphere - yep, any warming models have to account for a gas with a 100% margin of variability.