But should a moment for self-reflection arise, campaigners against climate change could do worse than take a look at the work of Stephen McIntyre, who has emerged as one of the climate change gang's Most Dangerous Apostates. The reason for this distinction? He checked the facts.

The retired Canadian businessman, whose self-described "auditing" a few years ago prompted a Congressional review of climate science, has once again thrown EnviroLand into a tailspin. In September, he revealed that a famous graph using tree rings to show unprecedented 20th century warming relies on thin data. Since its publication in 2000, University of East Anglia professor Keith Briffa's much-celebrated image has made star appearances everywhere from U.N. policy papers to activists' posters. Like other so-called "hockey stick" temperature graphs, it's an easy sell—one look and it seems Gadzooks! We're burning ourselves up!

"It was the belle of the ball," Mr. McIntyre told me on a recent phone call from Ontario. "Its dance card was full."