Wool is a versatile and popular fiber used in a wide range of fashion products, from sweaters and coats to suits and dresses.
In fact, sheep wool is the most common animal fiber used in the fashion and textile industry, accounting for 1% of the global fiber market in 2021.
But what is the environmental impact of wool production?
The animal fiber industry produces about 35 million tonnes of CO2e each year, with sheep wool responsible for nearly 98% of this total.
In this article, we will take a closer look at the environmental impact of wool, including the key factors that contribute to it, and sustainable alternatives to conventional wool.
What are the main emissions during the production of wool fiber?
Various Life Cycle Assessment (LCA) studies show that up to 75% of wool's environmental impact can be traced back to sheep. The main culprits are two greenhouse gasses, methane and nitrous oxide, which make up 93% of this impact.
Did you know that a single sheep produces over 30 liters of methane each day? Methane is a greenhouse gas that is 28-34 times more potent than carbon dioxide in terms of its global warming potential impact.
The other main gas released is nitrous oxide. Nitrous oxide comes from the nitrogen in sheep’s dung and urine, while the rest of the emissions come from sheep food, the fuel used in farm vehicles, and the energy used during shearing.
How to allocate the environmental impact of wool?
When assessing the environmental impact of wool, it’s equally important to take into account all the other products of sheep farming. That’s because sheep farming doesn’t just produce wool, it provides other useful products like meat, milk, lanolin (a wax obtained from wool), and manure-nutrients.
As a result, we need to distribute the environmental impacts of sheep farming fairly and practically among its different products to reflect their contributions as accurately as possible. This process, called “allocation”, plays a crucial role in determining the outcomes of LCAs for wool production.
PEFCR and wool
Before we delve into the parameters for estimating the carbon footprint of wool, let's briefly explain the two guidelines we'll be following: PEFCR and the EF 3.1 database.
PEFCR stands for Product Environmental Footprint Category Rules, and it's a set of guidelines for assessing and communicating the environmental performance of products in a specific category. In the context of apparel and fashion, PEFCR provides rules and criteria for evaluating the environmental impact of clothing and accessories throughout their life cycle.
By following PEFCR, companies in the apparel and fashion industry can adopt standardized methods for measuring and reporting their products' environmental footprints. This can help consumers make more informed choices based on the environmental impact of the products they purchase.
The PEFCR guideline is based on the biophysical allocation method, which means that the environmental impact of wool production is allocated based on the amount of protein in the wool. Based on the PEFCR guidelines, 23.6% of the emissions are assigned to the wool while 73.8% is assigned to the milk and the remaining 2.5% is assigned to the meat produced.
The EF 3.1 database (commissioned for development by the European Commission) is a collection of data on the environmental impact of different products and materials. The EF 3.1 database, which is complementary to the PEFCR guideline, has evaluated wool emissions and their environmental impacts.
Parameters for estimating the carbon footprint of 1 kg of wool fiber
Studies on sheep farming have revealed that most of the environmental impact occurs prior to the sheep leaving the farm, during the cradle to farm-gate stage.
According to these studies, more than 80% of the climate change, eutrophication (water pollution), and land use issues were attributed to this specific stage, with fossil fuel demand during this stage accounting for nearly 50% of the total impact.
With this in mind, it's important to consider the following parameters when conducting a life cycle assessment for wool:
To understand how much wool is produced on a sheep farm, we need to know the different types of sheep on the farm, and how much wool each type of sheep produces. For instance, lambs generally produce less wool with finer fibers. This means that lamb's wool may be used for different things than the wool from older sheep.
Additionally, different sheep breeds produce different amounts and qualities of wool. For example, Merino sheep are known for their fine wool, while Lincoln sheep produce coarse wool. The yield of wool can also vary within a breed depending on factors such as genetics, nutrition, and management practices.
The yield of the sheep has a direct impact on the carbon footprint of kg of wool. For example, The EF 3.1 database assumes that the average sheep in Australia produces 6-7 kg of wool per year.
2. Manure management
For this parameter, we need to define how manure is collected and stored because this determines the amount of methane and nitrous oxide released. This includes the gasses coming directly from the manure as well as those caused indirectly.
For example, manure in Oceania and Sub-Saharan Africa has different amounts of nitrogen: 1.13 kg N/1000 kg animal/day in Oceania and 1.17 kg N/1000 kg animal/day in Sub-Saharan Africa.
The nitrogen content can contribute to the formation of greenhouse gasses like methane and nitrous oxide. In the case of sheep, about 1% of the nitrogen in manure that enters the soil is converted to nitrous oxide.
3. Feed production
Sheep can eat a variety of foods, including grass and other crops like cereals and brassicas. Sheep can graze on these foods directly, or they can be used to make silage or concentrates, which are given to the sheep as additional food.
For this parameter, we need to know how much and what type of food the sheep eat to understand the environmental impact of the food produced.
Sustainable alternatives to sheep wool
Regenerative land management can reduce the climate impact of animal fibers and enhance biodiversity, water quality, and soil health. To date, there are no official LCA studies to quantify the amount of the savings.
As a fashion brand, it can be challenging to find a wool supplier that fully embraces these regenerative land management practices. But not impossible.
Allbirds is set to introduce the world’s first net zero carbon shoe next year. This revolutionary footwear will be crafted from merino wool sourced from Lake Hawea Station, a New Zealand farm that has achieved carbon neutrality through a comprehensive regenerative land management program.
Another alternative is recycled wool is made from wool that has already been produced and used, and then recycled into new fabric.
A recent study found that the carbon footprint for 1 kg of recycled wool is 0.63 kg CO2 eq, while virgin wool has an impact of 10.4 kg CO2 eq. This means that the carbon footprint of recycled wool is approximately 16.51 times less than that of virgin wool, making it a solid option for a low-impact alternative.
While recycled wool is a sustainable alternative to virgin wool, it also has some drawbacks, such as shorter fibers, reduced strength, and a harsher texture. It may also be more expensive and have limited color options.
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- EF 3.1 Database
- Textile Exchange, Preferred Fiber and Material Matrix
- Textile exchange, 2023, Material Pathways: Accelerating action towards Climate+ goals
- Agricultural commodity statistics 2016, Research by the Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES)
- Zampori et. al., Suggestion for updating the Product Environmental Footprint (PEF) method, JRC Technical report, 2019
- Sandin et al., 2019, The environmental impact of textile fibers - what we know and what we don’t know- the fiber bible (part 2)
- Environmental impacts associated with the production, use, and end-of-life of a woolen garment, S.G. Wiedemann et al. 2020
- Guidelines for conducting a life cycle assessment of the environmental performance of wool textiles: https://iwto.org/wp-content/uploads/2020/04/IWTO-Guidelines-for-Wool-LCA.pdf
- EPA, 2020: https://www.epa.gov/snep/agriculture-and-aquaculture-food-thought
- 5PEFCR guidelines: https://eplca.jrc.ec.europa.eu/permalink/PEFCR_guidance_v6.3-2.pdf