In 2019, some of the largest fashion brands in the world put their names on science-based climate targets, saying they would reduce their greenhouse gas emissions 30 percent by 2030 in order to stay in line with a UN-endorsed pathway to keeping the climate from warming more than 1.5 degrees Celsius. Just a couple of years later, the Sustainable Apparel Coalition, which has over 130 brand members—including Amazon, Gap, H&M, Nike, and Under Armour—upped that target for its members to a 45 percent reduction in emissions by 2030. At the COP26 climate conference last week, 130 companies joined in an announcement that they would reach net-zero emissions no later than 2050.

But to reduce greenhouse gasses, fashion’s climate fight hinges on another commitment: cleaner factories.