(As Asimov pointed out, the the flat-earth types aren't far from being "wrong," since Earth deviates from being flat by only eight inches per mile. When it comes to matters of science, a spit in the ocean is still a spit in the ocean.)
The burden of proof, in any case, rests upon those who claim "AGW" is a clear and present danger. Those of us who believe the whole hypothesis is (1.) flawed and (2.) primarily a political straw-man being pushed upon the public as an excuse to expand tyranny really have only to sew doubt.
We do not have to "prove" AGW is ridiculous or even "wrong," only that the proponents of this bogeyman are engaged in politics, not science.
Dr. Schmitt, when he resigned from the Planetary Society, late last year, may have put it best when he wrote, ""Consensus", as many have said, merely represents the absence of definitive science."