<i>In particular, why do you think those that argue that AGW is not happening should be given more of a benefit of the doubt? ... if you are going to argue that it's not happening, you have much more justification to do.</i><p>Because the scientific method dictates that the burden of proof is borne by the one proposing the theory. The opposite is impractical, because for most questions it's not possible to prove the open-ended negative.