The Intelligence Squared debate on global warming in NYC last month. Pull up a chair, grab a beer, and give it a listen. These guys are scientists, not politicians. Michael Creighton is one of the debaters, and NPR's Brian Lehrer is the moderator. I suggest the longer, unedited audio version.
Unfortunately, it's not set up as a true debate - more like a series of brief talks, but the exchanges get better towards the end. Still, interesting - except for that Brenda, who has nothing to say.
It's at The Reference Frame.
It left me wondering whether there is an ideal temperature for the earth, whether we can have any effect on it or not (which I doubt). Overall, quite enjoyable.