Financial Times: There is no question among serious thinkers that all major economies must participate in any solution to the threat of climate change. That is essential environmentally – because the challenge is a global one. It is also essential economically and politically – because no country wants to damage its economy or its citizens. But only the US, as the world’s pre-eminent power, can spearhead the effort. For that reason, it was encouraging to hear Hillary Clinton, secretary of state, say …