Neither cotton nor polyester is clearly better for the environment across the board. Polyester tends to produce higher greenhouse gas emissions over its life cycle and sheds persistent microplastics, while cotton demands enormous amounts of water, occupies agricultural land, and drives pollution through pesticides and dye effluent. The honest answer depends on which environmental problem you care about most, and what happens to the garment after you buy it.
Greenhouse Gas Emissions Favor Cotton, but Not by as Much as You Might Think
When researchers compare the full life cycle of a basic T-shirt from raw material to disposal, polyester consistently comes out worse on carbon. A life cycle assessment of fast-fashion T-shirts found that a polyester shirt produced about 9.6 kg of COâ‚‚ equivalent per functional unit, compared to roughly 6.1 kg for a cotton shirt.1Cleaner Waste Systems. From production to waste disposal: A life cycle assessment of fast fashion polyester and cotton T-shirts A separate assessment that focused specifically on carbon footprint confirmed the pattern: polyester T-shirts had a higher overall carbon footprint, driven largely by the energy-intensive production of polyester staple fiber and the COâ‚‚ released when polyester garments are incinerated at end of life.2Cleaner and Responsible Consumption. Carbon footprint of cotton, polyester, and blended T-shirts: A life cycle assessment considering wet processing differences
That gap matters, but it is not the whole story. Polyester’s carbon problem is concentrated at two ends: the fossil fuel extraction and chemical processing needed to create the fiber, and the emissions released when discarded garments are burned. Cotton’s emissions are more spread out across farming, fertilizer production, water pumping for irrigation, and manufacturing. The carbon comparison also shifts depending on how long you keep the garment, how you wash it, and what happens to it when you are done.
Water and Land Tell a Different Story
Cotton is one of the thirstiest crops in commercial agriculture. It supplies roughly a quarter of all global textile fibers, and growing it involves substantial water use along with impacts like eutrophication and toxicity from pesticides and fertilizers.3Nature. Environmental impacts of cotton and opportunities for improvement Depending on the country and whether the crop is rain-fed or irrigated, water consumption per kilogram of raw cotton fiber can vary enormously, but in arid cotton-growing regions the draw on local water supplies is severe. The Aral Sea disaster, though decades old, remains the most famous example of what cotton irrigation can do to a landscape at scale.
Polyester, by contrast, needs very little water to manufacture. It is synthesized from petrochemicals in industrial facilities, so its footprint on freshwater resources is a fraction of cotton’s. If your primary concern is water scarcity, polyester looks significantly better. But polyester’s advantage here comes with an asterisk: the fossil fuels it depends on carry their own extraction footprint, including habitat disruption and the risk of oil spills, which are water-related damages of a different kind.
Land use also separates the two fibers. Cotton fields compete with food crops and natural ecosystems. In parts of sub-Saharan Africa, expansion of cotton farming has been identified as a driver of major land use change and biodiversity loss in savannah ecosystems.4Springer. Cotton expansion and biodiversity loss in African savannahs, opportunities and challenges for conservation agriculture: a review paper based on two case studies Polyester takes up factory space, not farmland. For anyone thinking about how clothing relates to deforestation and wildlife, that distinction is meaningful.
Microplastic Pollution Is Polyester’s Biggest Liability
This is the environmental category where polyester looks worst compared to cotton, and it is one the general public has only recently started paying attention to. Every time you wash a polyester garment, it sheds tiny plastic fibers into the water. Textiles are now recognized as a major source of microplastics in the environment, and polyester fibers, which make up roughly two-thirds of global textile production, lead the way. Staple-length polyester fibers are especially prone to shedding because their shorter ends break free more easily.5PubMed. Decoding microplastic shedding from cotton/polyester blends: An analysis through fiber identification
The scale is striking. Research on polyester fabrics has found that a single load of laundry can release thousands of microplastic particles per liter of wastewater, with the exact count depending on the weave structure of the fabric.6Scientific Reports. Weave structures of polyester fabric affect the tensile strength and microplastic fiber emission during the laundry process These tiny fragments interact with ecosystems, accumulate in aquatic organisms, and have been found in everything from deep-sea sediment to drinking water.7PubMed Central. Microplastics in Wastewater by Washing Polyester Fabrics
Cotton also sheds fibers when washed, but the crucial difference is what happens to those fibers afterward. Controlled biodegradation experiments have shown that cotton microfibers degrade in natural aquatic environments, while polyester microfibers persist for extremely long periods.8PubMed. Microfibers generated from the laundering of cotton, rayon and polyester based fabrics and their aquatic biodegradation Cotton fibers submerged in seawater do degrade more slowly than those buried in soil, and cold water slows things further, but they still break down in a way that synthetic fibers simply do not.9Textile Research Journal. Effect of cotton fabric properties on fiber release and marine biodegradation If microplastic accumulation in the oceans and food chain is high on your list of worries, cotton has a real and substantial advantage.
Chemical Processing Pollutes on Both Sides
People sometimes assume that cotton, as a natural fiber, avoids the chemical contamination issues that come with synthetics. That is not quite right. Both fibers go through chemical-intensive manufacturing steps, and both create problematic waste streams in the process.
Cotton dyeing is a well-documented source of water pollution. Reactive dyes, the most common type used on cotton, require large quantities of inorganic salt and alkali to fix the color to the fabric. Dye that fails to bond with the cotton washes off into effluent, and the combination of dissolved solids, high oxygen demand, and unfixed dye makes cotton dye wastewater difficult to treat.10Journal of Cleaner Production. A review on developments in dyeing cotton fabrics with reactive dyes for reducing effluent pollution More broadly, dyes across the textile industry, whether reactive, dispersed, or vat-type, pose risks to aquatic ecosystems. In the absence of proper treatment, dye effluent can cause eutrophication, reduce oxygen levels, and introduce compounds with potential long-term toxicity.11PubMed Central. Textile finishing dyes and their impact on aquatic environs
Polyester has its own chemical problem: antimony. This element is used as a catalyst in manufacturing polyethylene terephthalate, the polymer that polyester fabric is made from. It shows up in finished polyester textiles at concentrations that can range from about 125 to 470 micrograms per gram of fabric, and a small percentage leaches out through contact with sweat.12PubMed. Antimony release from polyester textiles by artificial sweat solutions: A call for a standardized procedure At an industrial scale, antimony release is substantial. In China’s polyester fiber supply chain, the manufacturing stage alone has been estimated to release thousands of tons of antimony, with additional releases during dyeing, weaving, and landfill disposal of waste polyester.13PubMed. Dynamic flow and pollution of antimony from polyethylene terephthalate (PET) fibers in China Antimony is a regulated contaminant, and its presence throughout the polyester value chain is a genuine environmental and health concern that gets less attention than microplastics.
What Happens When You Throw It Away
The end-of-life stage is where both fibers run into trouble, though for different reasons. Polyester does not biodegrade in any meaningful timeframe. A polyester shirt in a landfill will sit there for centuries, and if it is incinerated instead, it releases COâ‚‚ from fossil carbon, worsening the garment’s total climate footprint. Conventional polyester creates pollution across its entire value chain, from production through use and end of life.14PubMed Central. Analysis of the polyester clothing value chain to identify key intervention points for sustainability
Cotton biodegrades, which sounds like a clear win. But in a landfill, where organic material breaks down without adequate oxygen, cotton generates methane, a greenhouse gas far more potent than COâ‚‚ over the short term. Research on discarded apparel found that landfilling natural fibers produces significant climate impact credits in the form of methane from decomposition, which partly offsets what might otherwise look like a clean disposal path.15Elsevier (ScienceDirect). Environmental impact of discarded apparel landfilling and recycling The takeaway: cotton’s biodegradability is an advantage in open, aerobic environments like soil or compost, but in a tightly packed landfill it creates a different kind of emissions problem.
Recycling Prospects Differ Sharply
Polyester has a structural advantage when it comes to recycling. Because it is a thermoplastic, it can be melted down and reformed. Recycled polyester fiber made from used PET bottles cuts greenhouse gas emissions by roughly 60% and fossil resource use by about 85% compared to virgin polyester, according to life cycle assessments of bottle-to-fiber recycling.16Environmental Research. Life cycle assessment and circularity of polyethylene terephthalate bottles via closed and open loop recycling That is a dramatic improvement. Mechanical recycling has a better environmental profile than chemical recycling, though chemically recycled fibers can serve a wider range of applications.17Resources, Conservation and Recycling. Open-loop recycling: A LCA case study of PET bottle-to-fibre recycling
Cotton recycling is harder. Mechanical recycling, the most common method, shortens the fibers and degrades their quality, which limits how much recycled cotton you can blend into new yarn before the fabric suffers. Chemical recycling of cotton can improve fiber quality, but the processes are expensive, carry their own environmental impacts, and remain difficult to scale industrially.18Next Chemical Engineering. Textile waste to cotton yarn: Technologies, challenges, and future directions Blended fabrics, which combine cotton and polyester in a single garment, are especially problematic because separating the two fiber types is complex and often not economically viable. If you have ever looked at a clothing label and seen “60% cotton, 40% polyester,” that garment is essentially unrecyclable with current mainstream technology.
Policy is starting to push the needle. France pioneered an extended producer responsibility program for textiles that has tripled collection and recycling rates since 2006, with material recovery rates reaching about 90%, half of which goes to direct reuse.19PubMed Central. Developing a national programme for textiles and clothing recovery The European Union has since moved toward broader textile waste regulations that may eventually make such programs standard rather than exceptional.
The Use Phase Matters More Than Most People Realize
Most environmental comparisons between cotton and polyester focus on raw material production, and that framing misses a lot. Fiber content influences how consumers actually use and care for clothing, including how often they wash it, at what temperature, and how long they keep it. When the use phase is left out of comparisons, major environmental problems associated with that stage, such as microplastic shedding from polyester during laundry, get excluded from the calculation entirely.20QUT ePrints. Does use matter? Comparison of environmental impacts of clothing based on fiber type
Polyester garments tend to dry faster and wrinkle less, which can mean lower energy use per wash cycle and less ironing. Cotton garments are typically washed at higher temperatures and tumble-dried more often, increasing energy consumption. But polyester garments are also more associated with fast fashion and shorter ownership cycles, which can cancel out any per-wash savings by increasing the total number of garments consumed. A polyester shirt that gets worn ten times before being thrown away has a much higher per-wear impact than a cotton shirt kept for years, regardless of which fiber looks better on a factory-gate comparison.
Organic and Regenerative Cotton Change the Math
Not all cotton is created equal. Organic cotton systems skip synthetic nitrogen fertilizers, which are a major driver of conventional cotton’s greenhouse gas footprint. A comparative life cycle assessment found that organic cotton production generated about 0.77 tons of COâ‚‚ equivalent per acre, compared to 1.61 tons for conventional cotton, a reduction of roughly 52%. The difference was driven almost entirely by fertilizer management, with organic systems relying on compost and manure instead of synthetic nitrogen.21Frontiers. Measuring cotton’s environmental burden: a dual LCA–emergy framework for conventional and organic systems
Regenerative agriculture takes this further by attempting to rebuild soil health, sequester carbon, and reduce water runoff. A life cycle assessment of homewear made from a blend of regenerative cotton and recycled post-industrial cellulosic waste found a climate change impact nearly 54% lower than conventional cotton homewear. When carbon sequestration credits from regenerative farming were factored in, the advantage grew to over 80%. Water consumption also dropped substantially, from about 4.7 cubic meters per functional unit down to about 1.5.22Journal of Cleaner Production. Towards circular textiles: Life cycle assessment of homewear produced from regenerative cotton and post-industrial waste versus conventional cotton These are still niche supply chains, but they suggest that the environmental ceiling for cotton is much higher than what conventional farming delivers.
Climate Vulnerability and Supply Chain Risk
One dimension that rarely comes up in fiber-versus-fiber environmental debates is how resilient each supply chain is to climate change itself. Cotton, as an agricultural crop, is directly exposed to weather extremes. In Australia, one of the world’s major cotton producers, roughly 83% of the crop is irrigated and delivers about 92% of national production. El Niño years tend to reduce rainfall and suppress yields, while La Niña years cluster in multi-year runs that favor large irrigated harvests.23Elsevier (European Journal of Agronomy). Climate and agricultural risk: Assessing the impacts of major climate drivers on Australian cotton production As climate patterns become more volatile, cotton production faces increasing risk of boom-and-bust cycles that ripple through global textile supply chains.
Polyester, being manufactured from petrochemicals in controlled facilities, is not subject to the same kind of weather risk. Its supply chain is vulnerable to oil price shocks and geopolitical disruption in fossil fuel markets, but not to droughts, floods, or growing-season heat waves. In a world where both climate instability and fossil fuel transition are accelerating simultaneously, both fibers face long-term supply uncertainty of different kinds. Cotton faces nature. Polyester faces regulation and the energy transition. Neither is a safe bet as a primary global textile material over the next several decades, which is part of why the industry is so interested in diversifying toward fibers like lyocell, hemp, and recycled blends that sit outside both risk categories.