In order to gain some understanding of the global climate system, we must first understand what the earth has been capable of, regarding climate change, before, man could have possibly had an effect, so that current trends can be examined in the right context.
So I emplore all of you, please google, "laurentide ice sheet" and "wisconsin glaciation"
The web sites that come up under these searches will give you a good feel for climate history, and put the current Al Gore claims in the right context.
The only downside is you will have to read, and learn to make your own opinion based on facts, rather than accept someone else's opinion.
Enjoy.