Less than two weeks ago, Boris Johnson told the General Assembly of the United Nations that “when Kermit the frog sang ‘It’s Not Easy Bein’ Green’, I want you to know he was wrong.” Perhaps not since Neville Chamberlain returned from Munich in September 1938 declaring “peace in our time” has a British prime minister said anything so spectacularly mistimed. At least it took a year before Britain was at war with Nazi Germany. Within days of Johnson’s comments, energy problems were surfacing around the world, from natural gas shortages in Europe to power cuts in China. The global energy crisis changes everything. Not least, it will make the cost of going green a great deal trickier.