Water vapour confirmed as the major player in climate change...

"...This study confirms that what was predicted by the models is really happening in the atmosphere," said Eric Fetzer, an atmospheric scientist who works with AIRS data at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Water vapor is the big player in the atmosphere as far as climate is concerned." So, there's more to it than CO2...more, here... and here...

and here...The entire issue of water vapor feedback is very important in forming a view on whether increased CO2 content is a big or little problem. Both water vapor feedback and clouds have been identified as critical issues since at least as early as the Charney Report in 1979 and I suspect that much of the difficulty in making much (any) progress in reducing the uncertainties in climate models relates to the difficulty in reducing uncertainty in this area. If one were managing climate model engineering in the same way as space station engineering, I would really focus on this area... but of course the science is quite settled...