Just to throw another log on the fire,
(carbon and all):
It's not just about CO2 anymore.
http://news.bbc.co.uk/1/hi/sci/tech/4419880.stm
I find this 'water vapor feedback` possibility most alarming.

Pragmatist

Murphys Law - "Whatever can go wrong will."
McTavishes Corrolary - "And at the worst possible time."
Schlemazzels Theorem - "And guess who gets it in the neck?"