The U.S, National Research Council has a quite good website explaining what is actually known about global warming and various approaches to dealing with the problem. The site is intended for the general public and presents the facts in a non-technical fashion while avoiding the extremes on both sides. The link is easy to remember: http://americasclimatechoices.org.
They have a downloadable 40-page booklet (PDF) entitled Climate Change: Evidence, Impacts, and Choices and a series of seven short videos. You can also order a package that includes two copies of the printed booklet together with a DVD of the video series for $1 plus shipping.
The National Research Council, the National Academy of Sciences, National Academy of Engineering, and the Institute of Medicine together form the National Academies.by