The world is parched. In California, a record heat wave has exacerbated the western US’s worst drought in centuries. Water levels in Europe’s Rhine River have been so low that at times over recent weeks this vital European waterway has been all but impassable to shipping. Asia’s longest river, the Yangtze, has struggled to feed farms and hydroelectric stations. Crops have wilted in the heat from India to the American Midwest. Scientists have long warned of the threats climate change poses to the stability of the global economic system. The severity of drought conditions this summer shows that the crisis is already here — and governments haven’t done nearly enough to prepare for it.