It is now firmly established, repeated ad nauseam in the media and elsewhere, that the debate over global warming has been settled by scientific consensus. The subject is closed. It seems unnecessary to labour the point, but here are a couple of typical statements: "The scientific consensus is clear: human-caused climate change is happening" (David Suzuki Foundation); "There is overwhelming scientific consensus" that greenhouse gases emitted by man cause global temperatures to rise (Mother Jones). Back when modern science was born, the battle between consensus and new science worked the other way around. More often than not, the consensus of...