The Colorado [River] originates in the Rocky mountains and traverses seven US states, watering cities and farmland, before reaching Mexico, where it is supposed to flow onwards to the Sea of Cortez. Instead, the river is dammed at the US-Mexico border, and on the other side the river channel is empty. Locals are now battling to bring it back to life. There are few more striking examples of what has come to be known as “environmental injustice” – the inequitable access to clean land, air and water, and disproportionate exposure to hazards and climate disasters. Water in particular has emerged as a flash point as global heating renders vast swaths of the planet ever drier.