As regards water vapor as a forcer, it has been tested, by the Pinatubo data, as the article notes "the models are probably getting the broader picture reasonably correct".
IMO, the way this is heading is pretty clear: 5 years or a decade from now the more scientifically literate skeptics here will be saying 'Well, in the mid 00s, we still had reason to be skeptical, and after all things didn't turn out to be as dire as suggested by the more pessimistic models."
I have a better explanation. Pinatubo displaced millions of tons of ash, SO2 and SO3 into the atmosphere in the percent levels. This caused cloud formation. This caused the cooling.
If the greenhouse hypothesis is correct we should see higher concentrations of CO2 and higher temperatures as we travel upwards. That is not the case. So the global warming/greenhouse hypothesis due to CO2 is incorrect.