citing the source in the most proper way imaginable, I'd say. Utterly laudable. (Personally I'm too lazy to do so)
This cartoon may be a bit of a bomb in the ongoing discussion but I trust all participants to have enough of a sense of humour to enjoy it nevertheless. As far as I can see it has funny aspects both from the perspective of a global warming believer and a global warming disbeliever.
Maybe, if we can share a laugh about the same thing, we'll stop quarrelling?