One factor in the anthropogenic global warming debate is the unwillingness of many of the bureaucratic based supporters (which is most of the ones who have scientific knowledge) to conclude that their results do not support the hypothesis when that is the fact. One area in which the models have failed is in the prediction of formation of low level clouds as water vapor in the atmosphere increases. Actually the fact that the general circulation models fail at this is the reason the modelers use cloud formation as an input parameter. The assumption the modelers make becomes a self-fulfilling prophesy for higher temperatures. (It appears that the low altitude cloudiness increases as water vapor is added to the atmosphere, which increases the amount of solar energy reflected to space, and is a negative feedback rather than a positive feedback as the modellers assume.) Here is a discussion of this by Dr. Roy Spencer.

http://www.drroyspencer.com/2009/01/new-study-doesn%e2%80%99t-support-climate-models-but-you%e2%80%99ll-never-hear-about-it/