By Andrew Stuttaford
A 19th-century Scottish journalist, songwriter, and poet is not an obvious guide to a 21st-century intellectual and political phenomenon, but when it comes to making sense of climate-change zealotry, there are worse choices than Charles Mackay (1812–89), the author of Extraordinary Popular Delusions and the Madness of Crowds (1841), an acerbic, often drily amusing study of the frenzies — from witch mania to the tulip bubble — that regularly possess our supposedly sophisticated species.