In 2007 polyester overtook cotton as the world’s dominant fiber, the amount of poly produced annually increased from 5.8 million tons to 34 million tons, according to Technon Orbichen. By 2015, that number is expected to triple to 99.8 million tons! One reason for the poly boom is that the Earth has only so much farmland. Cotton must share this limited space with the world’s food crops.
Derived from crude oil, Polyester is a polymer, or a long chain of repeating molecular units. When melted, it has the consistency of cold honey, and when pressed through a straining device called a Spinneret, you get long continuous filaments. Stretching the filaments into long fibers allows them to then be woven into fabric.
Its biggest drawback is that it requires a lot of energy, which means burning fuel for power and contributing to climate change. But to put that in perspective, Linda Greer, director of the health program at the Natural Resources Defense Council, says you actually release more carbon dioxide burning a gallon of gas than producing a polyester shirt.
In theory, cotton is biodegradable and polyester is not. But the thing is, the way we dispose of clothing makes that irrelevant. For cotton clothes to break down, they have to be composted, which doesn’t happen in a landfill.
“They need to go to a facility that chops them up and then gives them water and oxygen and nutrients and that kind of thing,” Greer tells Quartz. “Suffice it to say that very, very little solid waste has that disposal destiny.”
Ecologically speaking, polyester is no worse—and may actually be better—than conventional cotton. According to Marc Bain of Quartz Media, a comprehensive study (pdf) of various textiles by the European Commission found that environmental impacts per kilogram of fiber are higher for cotton than other materials, primarily because of the large quantities of toxic pesticides and fertilizers required to grow cotton, which also requires a great deal of water (pdf).
Polyester, by contrast, uses very little water, and while producing it involves some toxic chemicals, those generally aren’t released into the environment (pdf). It can also be made from recycled plastic bottles, turning your garbage into clothing.
The bottom line is that while the rise of polyester is not good news for the planet, a big increase in cotton production wouldn’t be any better. The global demand for clothing has surpassed cottons ability to provide enough of the fluff. Polyester with its new look and feel, additional benefits such as moisture wicking and sun protection, has become and will continue to be highly desirable by top fashion houses and new designers such as SJC Sport Couture.