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The climate impact of cotton depends on how often you wash it and how long you wear it

DAILY SCIENCE

The climate impact of cotton depends on how often you wash it and how long you wear it

In a new study, researchers assess impacts from the cultivation, manufacturing, and use of textiles made of the world’s most common natural fiber
October 10, 2023

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What to wear is a consumer decision that virtually everyone can—and indeed must—make, over and over again. But many sustainability studies of cotton garments have ignored the impact of how consumers wear and take care of their clothing, according to a new review.

Cotton is the most commonly used natural fiber used in clothing, accounting for about one-quarter of global textile fibers. “Cotton grows on more than 30 million hectares of cropland in 85 countries and regions, and more than half of all countries and regions are involved in the international cotton textile trade,” an international team of researchers writes in the journal Nature Reviews Earth & Environment.

For their study, they assembled evidence from previously published life cycle analyses tracing the water use, toxicity, eutrophication, and carbon emissions associated with cotton garments across different phases of their production and use.

Much of the impact comes down to the devil in the details—that is, where and how the cotton is cultivated and garments are manufactured, and how people wear them over time.

For example, the lion’s share of water use generally happens during cotton production and manufacturing. Cotton is a water-hungry crop and contributes to water scarcity in many areas; climate change is likely to exacerbate these challenges in the future. About half of cotton grown worldwide is irrigated, and textile dyeing also tends to be water intensive. Against these processes the water used to launder clothing is barely a drop in the bucket.

 

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But, in areas where electricity is carbon-intensive, the use phase of cotton garments often has a bigger carbon footprint than the production phase. That’s especially true if people do a lot of machine drying, as is common in the US.

To reduce the environmental footprint of your cotton jeans and t-shirts, you can wash them less frequently, air dry rather than tumble dry them (both of which also extend the lifespan of garments), run the washing machine at full capacity and with less detergent, and minimize ironing.

It’s also important to reduce the siren song of fast fashion, purchasing fewer new clothes; choosing higher quality, more durable ones; holding on to them for longer; and altering, repairing, and reselling clothes to extend their use.

The carbon footprint of a cotton garment is anywhere from 3 to 62 kilograms of carbon dioxide, according to different studies included in the review. “Strikingly, this range indicates that in most cases shown here, each garment use causes [greenhouse gas] emissions of the same order of magnitude as the mass of the garment,” the researchers write.

Source: Zhang Z. et al.Environmental impacts of cotton and opportunities for improvement.” Nature Reviews Earth & Environment 2023.

Image: Photo by Seven Seven on Unsplash.

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