Sometimes the simple answer is also the hardest; eventually, you've got to buckle down and start reading, and Global Warming: The Complete Briefing lives up to its name.
Sir John Houghton is, of course, also presenting a somewhat digested message. His book is not a compilation of papers and reports. But he does go into enough detail to allow readers to think for themselves rather than simply choose who to trust. I should say, before I go much further, that the version I read was not the most recent edition. Given how quickly the field of climatology is progressing, and how fast the climate itself is changing, I recommend going after the most recent edition you can find. There are currently at least four.
Details included here range from exactly how the relationship between incoming sunlight and the greenhouse effect can be calculated to how we know that carbon dioxide is a greenhouse gas and who figured that out. Dry? Of course it's dry, but that doesn't mean it's boring or badly written. It takes some work to get through this book, but you'll be glad you did.
If other books on the subject are directions, this one is a map. Directions are good--until you miss a turn or the route unexpectedly changes. Maps give you the bigger, broader view, and allow you to plot your own course no matter what unexpected questions come your way.
Houghton, J. (1997) Global warming: The complete briefing. Cambridge: Cambridge