The climate change industry always needs a fresh angle, and the latest is that carbon emissions are an economic threat akin to mortgage-backed securities before the financial panic. The analogy comes from Hank Paulson—and if he has spotted a bubble this time, we guess one out of two is an improvement on zero out of one.

With the travelling billionaire wilburys of Tom Steyer and Michael Bloomberg, the former Treasury Secretary put out a 197-page study last week that predicts the costs of a warming catastrophe. Their "Risky...