The sea will save us. We have hardly begun to exploit, or corrupt, the Earth’s vast reservoir of resources. Seawater, desalinated by filtration, will refresh dehydrated humanity. Sea will replace soil for farming; aquaculture will succeed agriculture. When and if we run out of space for fish production, we will eat the planet’s one effectively inexhaustible food source: the heirs of Mary Berry and Auguste Escoffier will offer recipes for plankton.