Via a commenter, I see that James Randi, who has sort of a history of spotting scientific fraud, has apparently lost his mind and become a “denier”:
The Intergovernmental Panel on Climate Change (IPCC) — a group of thousands of scientists in 194 countries around the world, and recipient of the 2007 Nobel Peace Prize — has issued several comprehensive reports in which they indicate that they have become convinced that “global warming” is and will be seriously destructive to life as we know it, and that Man is the chief cause of it. They say that there is a consensus of scientists who believe we are headed for disaster if we do not stop burning fossil fuels, but a growing number of prominent scientists disagree. Meanwhile, some 32,000 scientists, 9,000 of them PhDs, have signed The Petition Project statement proclaiming that Man is not necessarily the chief cause of warming, that the phenomenon may not exist at all, and that, in any case, warming would not be disastrous.
Happily, science does not depend on consensus. Conclusions are either reached or not, but only after an analysis of evidence as found in nature. It’s often been said that once a conclusion is reached, proper scientists set about trying to prove themselves wrong. Failing in that, they arrive at a statement that appears — based on all available data — to describe a limited aspect about how the world appears to work. And not all scientists are willing to follow this path. My most excellent friend Martin Gardner once asked a parapsychologist just what sort of evidence would convince him he had erred in coming to a certain conclusion. The parascientist replied that he could not imagine any such situation, thus — in my opinion — removing him from the ranks of the scientific discipline rather decidedly.
History supplies us with many examples where scientists were just plain wrong about certain matters, but ultimately discovered the truth through continued research. Science recovers from such situations quite well, though sometimes with minor wounds.
I strongly suspect that The Petition Project may be valid.
Emphasis mine. I think that claiming that there is a “consensus” and that “the science is settled” are semantically equivalent to “I can’t imagine any such situation.” Such people are many things, but they are not people who truly respect, or even understand, science. They are politicians, encouraging political acts.
[Update a while later]
I’ve deleted my reference to Little Green Footballs, pending the outcome of an ongoing civil email conversation with Charles.