|What I'm curious about is whehetr Mr. Fuller's confusions about the science are typical of a large group of people who listen only to certain sources, or are they unique to him?In particular, the water vapor business seems to me what any normal person would gather from reading Lindzen's highly misleading Wall Street Journal Op-Ed from a month or so ago. There Lindzen deliberately conflated cloud feedbacks (about which there is still considerable uncertainty) with the larger and much more certain water-vapor feedback, claiming that the relationship between the two meant that uncertainty about one applied to both. Obviously, it doesn't. But any ordinary person reading Lindzen would come away deeply confused on the point.Increasing surface temperatures necessarily force more water into the air as vapor. More water vapor means more warming since H2O is a greenhouse gas. There is no question about that, there has been none for over 100 years, and the magnitude of the effect is known pretty well from modeling (combined water vapor + change in lapse rate a negative feedback that results from the same process has a range of 0.8 to 1.2 (Soden and Held, 2006 see IPCC AR4 Ch8, figure 8.14, discussion in 18.104.22.168 around p. 631). Increased water vapor and temperatures ought to have some effect on clouds, but the relationship is not simple: higher temperatures mean a higher water vapor concentration is needed before condensation forming clouds occurs, so depending on the detailed profile of changes, the feedbacks could lead to more or less clouds, with altitude and cloud-type dependencies. Lindzen's public conflation of the uncertainty in cloud feedbacks with that in water vapor at this point is hard to credit any positive motive for.Worse than all that though, the continued claims by Lindzen and some other "skeptics" that climate sensitivity must be low, based on one or other poorly understood issues, has to deliberately ignore the lines of evidence not just from models, but from present observations, from relatively recent and ancient paleoclimate, and all those other sources of information on the question as summarized by Knutti and Hegerl (2008).And to actually have a case against action, they not only have to argue that sensitivity *could* be low, the argument has to be that it *cannot be high*, because it is the significant chance that climate sensitivity is indeed higher than the currently settled-on range that is the most urgent call to action.The whole stance is intellectually bankrupt. Why do so many, like Fuller, fall for it? Lack of critical thinking skills? Relying on the wrong sources and not reading any of the original literature (such as the papers I just cited)?