Denim's environmental impact is huge.
September is international fashion month, and in cities across the world, the newest designs are on display. Those trendy threads used to take six months to go from the shows to the shops, but today many are delivered to stores at the same time they're displayed on the catwalks.
Fast fashion—the brisk sale of cheap, trendy clothes (think H&M)—has resulted in a throwaway culture in the US. We buy five times as much clothing as we did in the 1980s, and we trash about 13 million tons each year, most of which ends up in landfills. Jeans are one of the few items we tend to keep for a long time, but their environmental toll is significant. We use huge amounts of water and chemicals to make them, though steps are now being taken to mitigate the impact. But with 2 billion jeans produced annually worldwide, it's going to take a large-scale sustained effort to make a meaningful change.