Praise be and Hallelujah. Michael Mann, a leading climate scientist, is now halfway to understanding climate change. It’s a pity it’s taken him this long, and he is still only halfway, but this is indeed an advance insofar as he’s caught up with what every economist on the planet has been shouting for decades now.

Leave aside whether climate change is actually happening— we all have our entrenched positions on that debate. My own view is that it’s so engrained in the establishment’s thinking that the fools are going to do something about it anyway, whatever the truth. We must therefore steer them towards pursuing the sensible option, which is a revenue neutral carbon tax. That’s where Mann comes in. “I would place a price on carbon,” he said recently. That’s the correct position, as William Nordaus has been pointing out at least since the 1990s, as the Stern Review for the UK government did, and as every economist who has even glanced at the problem has said.