Below is a link to a 58-minute film of Naomi Oreskes' lecture on global warming denial in the U.S.

I let the entire thing load up before trying to watch it because it is quite long. The film is made available by University of California Television.

"Polls show that between one-third and one-half of Americans still believe that there is 'no solid' evidence of global warming, or that if warming is happening it can be attributed to natural variability. Others believe that scientists are still debating the point. Join scientist and renowned historian Naomi Oreskes as she describes her investigation into the reasons for such widespread mistrust and misunderstanding of scientific consensus and probes the history of organized campaigns designed to create public doubt and confusion about science."

http://www.uctv.tv/search-details.asp?showID=13459

Or the film can be found at YouTube: http://www.youtube.com/watch?v=2T4UF_Rmlio

This film is well worth watching.