Paul Matthews has had a paper published in the journal Environmental Communication looking at global warming sceptics and their backgrounds:
Surveys of public opinion show that a significant minority of the population are skeptical about climate change, and many suggest that doubt is increasing. The Internet, in particular the blogosphere, provides a vast and relatively untapped resource of data on the thinking of climate skeptics. This paper focuses on one particular example where over 150 climate skeptics provide information on their background, opinion on climate change, and reasons for their skepticism. Although these data cannot be regarded as representative of the general public, it provides a useful insight into the reasoning of those who publicly question climate science on the Web. Points of note include the high level of educational background, the significant numbers who appear to have been converted from a position of climate concern to one of skepticism, and the influence of blogs on both sides of the climate debate.
There is a preprint here and Paul's blogpost on the subject is here.