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.