Style is supposedly forever. But the garments needed to conjure up eternal chic are spending less time on shop racks and in homes than ever before. Global clothing production doubled between 2000 and 2014, as apparel firms’ operations became more efficient, their production cycles became quicker and fashionistas received more for their money. From just a few collections a year, fast-fashion brands such as Zara, owned by Spain’s Inditex, now offer more than 20; Sweden’s H&M manages up to 16.

Dressing to impress has an environmental cost as well as a financial one. From the pesticides poured on cotton fields to the washes in which denim is dunked, making 1 kilogram (2.2 pounds) of fabric generates 23 kilograms (50.7) of greenhouse gases on average, according to estimates by McKinsey.

Because consumers keep almost every type of apparel only half as long as they did 15 years ago, these inputs quickly go to waste. The latest worry is shoppers in the developing world, who have yet to buy as many clothes as rich-world consumers but are fast catching up.

Most apparel companies know that sooner or later, consumers’ awareness of this subject will rise. That is a worry. Various furors in the 1990s and afterward over the working conditions of people making goods for firms such as Nike, Wal-Mart and Primark badly damaged brands.

The clothing industry cannot afford to appear so ugly again.

One obvious way in which firms can answer environmental concerns is to use renewable energy to power their facilities. Beyond that, they can cut back sharply on water and chemical use; and they can develop new materials and manufacturing processes that reduce inputs.

The record in this regard is mixed. H&M was the largest buyer in the world of “better cotton” last year — that is, cotton produced under conditions to eliminate the nastiest pesticides and encourage strict water management.. Nike’s Flyknit method of weaving items, including trainers, reduces waste by 60 percent in comparison with cutting and sewing.

But for many firms, research and development into new materials and methods is not a priority. A handful of brands encourage customers to recycle old clothes by returning them to stores. But almost all apparel today is made of a mix of materials — very often including polyester. Separating them out is difficult and mechanical methods of recycling degrade fibers. Chemical methods are too expensive to be viable.