Several people recommended the Climate of Doubt segement on Frontline this week. While it is good and covers some of the bases it does not represent just how strong the science is showing that global warming exits, much of it has a human origin mostly from burning fossil fuels, and the rate of change is so rapid that there will be severe consequences this century. It is still worth watching though:
A more interesting resource is Merchants of Doubt by Erik Conway and Naomi Oreskes, which goes deeply into the industry of twisting the nature of science itself by taking advantage of the high rate of scientific illiteracy in America. In particular it looks at Ozone, DDT, tobacco and global warming and the small group of handmaidens of doubt who trace trough all of them. Excellent read.