The Carbon Footprint of Cotton

"You Ask, We Answer" – brought to you by Carbonfact's Head of Science. Each week Laurent Vandepaer answers one of your questions about sustainable materials, manufacturing impact, and energy transition in the apparel and footwear industry.

Before joining Carbonfact, Laurent led the integration of LCA into the sustainability and innovation efforts at On and performed LCA for other brands like Arc'teryx. Laurent also worked for several years in research with a PhD focusing on the deployment of LCA at a large scale.

Question: What is the carbon footprint of organic vs. conventional cotton? Does organic cotton consume less water than conventional cotton? 

Asked by the Head of Sustainability from an apparel brand

Durable, breathable, and renewable, cotton is one of the most widely utilized natural materials in the fashion and textiles industry. According to the Textile Exchange Materials Market Report for 2024, cotton accounted for 19.9% of all global fiber production in 2023, being the second most-used after polyester, and the most-used plant fiber.

Depending on the data and geographical source, cotton’s environmental footprint is between 6.07 kg CO2e and 1.15 kg CO2e. Conventional cotton farming often involves heavy use of chemicals. Pesticides applied to cotton can pollute the soil and both ground and surface water, with potential drift affecting nearby crops. Additionally, the widespread use of synthetic fertilizers to boost yields contributes to water contamination and substantial greenhouse gas emissions. 

The cotton market's lack of transparency makes it challenging to obtain reliable data. Complex global supply chains with multiple intermediaries make it challenging to trace cotton from farm to finished product; additionally, inconsistent data collection practices and varying standards across regions and LCA studies obscure the visibility of environmental and social impacts in the cotton lifecycle.

Cotton Production Process

Organic cotton is produced from the same plants as conventional cotton, but the key difference lies in its cultivation. Organic farming methods avoid using synthetic pesticides, chemical fertilizers, and other synthetic substances, focusing instead on natural processes to support plant growth and soil health.

• Cultivation: The growth of cotton plants, with organic farming using natural inputs like compost rather than synthetic fertilizers.
• Harvesting and ginning: Raw Cotton is harvested and the fibers are separated from the seeds.
• Opening, cleaning, blending, and carding: Raw cotton is cleaned and prepared for spinning.
• Spinning, weaving, or knitting: Cotton fibers are spun into yarn and then woven or knitted into fabric.
• Dyeing, printing, and finishing: The final stages where the fabric is dyed, printed, and finished for use.

This process is followed for both organic and conventional cotton, though organic methods aim to minimize environmental impacts at every stage.

Cotton Life Cycle Assessment Study

Recent cotton studies are limited, largely due to the market's lack of transparency. However, in 2021 the Better Cotton Initiative (BCI) commissioned a study to compare the carbon footprint of Better Cotton with conventional methods. 

The Better Cotton Initiative promotes sustainable cotton farming by improving water management, reducing pesticide use, and enhancing soil health. Better Cotton is not a specific type of cotton but operates as a labeling system for cotton grown under BCI guidelines. These guidelines include criteria such as efficient water use, reducing synthetic pesticide reliance, improving soil health through crop rotation, and ensuring fair labor practices. Find more on BCI principles and criteria here.

The study examines emissions from production to ginning in key regions like India, Pakistan, China, Brazil, and the U.S., aiming to reduce the environmental impact of cotton farming.

Here are some important factors highlighted by the BCI study when evaluating the cotton:

• Importance of fertilizer production: The BCI study reveals that fertilizer production is the largest contributor to GHG emissions in cotton production, accounting for 47% of total emissions on average. Organic cotton farming relies on natural fertilizers like compost and manure instead of synthetic nitrogen fertilizers, though the breakdown of these organic fertilizers in soil can still release nitrous oxide.
• Irrigation: Irrigation is the second-largest contributor to GHG emissions in cotton production, accounting for 17% of total emissions on average. Pumping, transporting, and distributing water requires energy, which generates emissions. The contribution of irrigation varies considerably by region, depending on rainfall, irrigation methods, and water sources.
• Fertilizer application: The application of nitrogen fertilizers results in emissions of nitrous oxide (N₂O), a potent greenhouse gas. Although fertilizer production is responsible for a larger share of emissions, the application itself contributes 12% of total emissions on average.
• Ginning: The ginning process, which involves separating cotton fibers from seeds, consumes energy and generates GHG emissions. The emissions intensity of ginning depends on the energy source used and the efficiency of the ginning plants. Ginning accounts for 11% of total emissions from Better Cotton production.
• Other sources: Other sources of GHG emissions, such as crop residue management, field operations, pesticides, and transportation of cottonseed to the gin, collectively contribute a relatively small share of total emissions.

(Source: 2021 Better Cotton Releases Study on GHG Emissions)

(Over 200,000 farm assessments from 2015-16 to 2017-18 analyzed, using the Cool Farm Tool to calculate GHG emissions. Better Cotton provided primary data on inputs, farm sizes, production, and locations, with gaps filled through desk research where necessary.)

In the study, it seems surprising that the emissions from fertilizer production are much higher than emissions from fertilizer application – a discrepancy that is not specifically addressed in the BCI study. As the study is from 2021, they likely used Global Warming Potential (GWP) values from the previous assessment report.

Limitations of the BCI cotton study LCA results

The study has several important limitations:

• Land use change impacts are not integrated into the analysis, only discussed qualitatively
• Data is self-reported, which may introduce bias
• Other studies suggest higher fertilizer application rates, warranting further investigation

Note: While we cite these results for reference, this does not constitute an endorsement of BCI cotton.

Cotton Carbon Emissions Differ Per Region

Regional differences in cotton emissions are influenced by the use of synthetic fertilizers and irrigation, which lead to higher emissions. In contrast, areas with more sustainable practices and renewable energy tend to have lower footprints. Climate conditions and soil management also contribute to these variations.

The chart below compares organic and conventional cotton, revealing that:

• Conventional cotton (blue) generally has the highest emissions, especially in the United States (6.07 kg CO2eq/kg), China (7.48 kg CO2eq/kg), and Brazil (5.73 kg CO2eq/kg), where synthetic fertilizers and irrigation are heavily used.
• Organic cotton (orange) tends to have the lowest emissions, particularly in countries like Kyrgyzstan (1.15 kg CO2eq/kg), Tajikistan (1.15 kg CO2eq/kg), and Turkey (3.18 kg CO2eq/kg), likely due to more sustainable farming practices and less reliance on synthetic inputs.
• The global average (world) follows a similar pattern, with conventional cotton showing the highest emissions, followed by organic.

The results show an unexpected finding: organic cotton in India has a higher environmental impact than conventional cotton. While this data comes from the EF3.1 database, limited documentation is available about its inventory and key modeling parameters. Several factors could explain this surprising result:

• Potential yield differences between organic and conventional farming
• Varying modeling assumptions between the two cotton types
• Possible data errors in the dataset

Our Science team is conducting further research on this topic and will share any new insights as they emerge.

(Data Source: EF3.1 database)

What is the Water Usage for Producing Cotton Fabric?

The challenge in comparing water usage between organic and conventional cotton lies in the fact that regional factors, such as climate and irrigation methods, play a significant role, making broad claims difficult. The water impact can happen at every stage of cotton production but is likely to be higher during farming and dyeing especially if these processes occur in water-deprived countries.

The EF 3.1 database provides water scarcity impact scores about water use relative to the local scarcity of water in different countries using the AWARE method. This is expressed in m³ deprived, meaning how much water the farms "take away" from the available local water supply. 

The global average for organic cotton is 125.6 m³ deprived while it is 87.28 m³ deprived for conventional cotton, indicating a higher water stress caused by organic cotton. For comparison: 

The average water use for organic cotton is higher because some countries that grow a lot of organic cotton use much more water than others. For example, countries like Kyrgyzstan, Turkey, and Tajikistan contribute a significant share of the global market, with 10%, 10%, and 5% respectively, and are driving up the global average:

• Kyrgyzstan: 444.24 m³ of water per kilogram of cotton
• Turkey: 188.61 m³ of water per kilogram of cotton
• Tajikistan: 464.23 m³ of water per kilogram of cotton

Despite these regional differences, there is no conclusive evidence from critically-reviewed studies that prove organic-cotton farming uses less water than conventional methods. Whether cotton is grown organically or conventionally does not necessarily determine the amount of irrigated water used.

Organic Cotton Fraud and Certifications

The total volume of organically farmed cotton is uncertain, largely due to widespread fraud in the market. This fraud typically occurs when conventional cotton is deliberately mislabeled as organic to capitalize on premium prices and growing demand. Several factors enable this deception:

• Weak supply chain traceability
• Inconsistent certification processes
• Limited oversight, especially in regions with fragmented supply chains
• Ability to blend or substitute non-organic cotton undetected

Organic cotton certification standards were developed to address these issues. These standards require farmers to:

• Maintain soil health
• Avoid synthetic fertilizers
• Prohibit hazardous pesticides
• Ban GMO use

 Here's an explanation of each part of the Organic Cotton Certification system:

Governments: To be legally sold as “organic”, raw cotton must come from farms certified under government-regulated organic standards. For example, India’s National Programme for Organic Production (NPOP) certifies a large portion of the world’s organic cotton, aligning with international standards.

Voluntary Standards Scheme Owners: Standards like Textile Exchange's Organic Content Standard (OCS) and the Global Organic Textile Standard (GOTS) use chain-of-custody models to track organic cotton volumes throughout the supply chain.

Certification Bodies: Governments and voluntary standard organizations like GOTS and Textile Exchange do not conduct certifications themselves. Instead, certification bodies verify compliance at farms and facilities, with different bodies focusing on different aspects of the supply chain. 

Should Brands Switch to Organic Cotton?

Organic farming systems have the potential to maintain and enhance the health of soils, ecosystems, and communities by utilizing ecological processes, biodiversity, and locally adapted cycles, instead of relying on external inputs that may cause harm. 

For example, rather than applying synthetic nitrogen fertilizers —which contribute to significant greenhouse gas emissions during production and use, and can negatively impact soil health and water quality— organic farmers use methods like crop rotation and green manures to naturally enrich the soil.

Brands can support farmers transitioning to organic cotton by partnering with them to promote low-carbon practices, investing in programs that encourage organic farming, and purchasing "in-conversion" cotton (cotton grown by farmers who are in the process of transitioning from conventional to organic farming methods) to help share financial risks during the certification period.

About Carbonfact

The cotton supply chain is among the longest and least transparent in the fashion industry, making brands susceptible to new regulations on supply chain due diligence and the demand for substantiating green claims with reliable, verifiable data.

Carbonfact is a Sustainability Platform, built specifically for apparel and footwear brands as well as manufacturers to measure the environmental impact of their products and take actionable steps to track and reduce their footprint. 

Carbonfact's platform displays detailed process steps not only for products, but also for each material and fabric used in your products. You can filter through your materials by supplier, raw material type, and any of your own custom properties.

Our Product Impact Simulation tool enables you to run what-if scenarios on a product level, where you can experiment with different materials preparation techniques, suppliers, renewable electricity share, or transportation methods, and build concrete company-level decarbonization scenarios.

(Carbonfact's platform)

Do you have questions about sustainable practices, manufacturing impacts, or energy transitions in the apparel and footwear industry? We'd love to hear from you! Comment, send us a DM on Linkedin, or email: youaskweanswer@carbonfact.com