Londoners have been getting used to some extra disruption as Extinction Rebellion, an environmental movement, has stepped up its campaign to persuade the government to treat climate change as a national emergency. Activists have stripped naked in parliament, smashed the entrance to Royal Dutch Shell’s headquarters and generally messed up traffic and train services around the capital.

It is tempting to satirise this as a bunch of well-off Britons (many with professional backgrounds) demanding a grand act of renunciation from the public — one that will principally fall on those less financially comfortable than themselves.

But they are right about one thing: despite the efforts of the past three decades, the world has yet to make much progress in containing growth in CO2 emissions. True, the EU-28 cut output by 12 per cent between 1990 and 2013 to 3.42 gigatonnes, and US growth has been constrained. But at the same time China’s output increased from 2.44Gt to 10.27Gt as the country has lifted hundreds of millions out of poverty; something that will continue. Beijing’s “Belt and Road” initiative envisions hundreds of new coal-fired power stations, of which 240 were under way in 2016. Overall, global emissions are up by 60 per cent.