Four years ago the world averted a humanitarian catastrophe—or seemed to. One giant cereal producer, Russia, invaded another, Ukraine. Fears of food shortages spread in poor countries unable to pay suddenly astronomical prices for wheat and other staples. Then the two foes agreed to let grain-laden ships sail from their Black Sea ports. Markets calmed; hunger vanished from the headlines. But not from destitute lives. The Ukraine war is thought to have killed more people in the global south than on the battlefields of eastern Europe. Now a war in the Gulf threatens a similar slow-motion calamity outside the theatre of conflict. The poor in Africa and Asia are already growing less on their plots and skipping meals. The UN’s World Food Programme warns that if the Strait of Hormuz is not open by mid-year, the more than 300m people who already struggle to feed themselves will be joined by another 45m. The world could help avert this outcome. The tragic reality is that it won’t.…