The Atacama Desert in northern Chile stretches from the Pacific to the Andes across a vast expanse of dramatic red-orange rock canyons and peaks. It is the driest desert on Earth—and so closely resembles the surface of Mars that NASA tested planetary rovers there.

Today, the Atacama has attained a less wondrous distinction: as one of the world’s fast-growing dumps of discarded clothes, thanks to the rapid mass production of stylish, inexpensive clothes known as fast fashion. The phenomenon has created so much waste, the United Nations terms it “an environmental and social emergency” for the planet. The challenge ahead is turning off that tap.

The numbers tell the tale. Between 2000 and 2014, clothing production