Here's the suggestion:
Rent a copy of An Inconvenient Truth. Invite a group of friends over. and watch it, then watch this interesting video (streamed via the web and a computer onto your gigantic flat screen).
Randomly divide the group into Anthropogenic Global Warming zealots and AGW deniers. Give no clues as to which individuals might be playing Devil's Advocate, and which might be expressing genuine opinions.
Stand back and watch the fun.
Here's the video in its entirety.