The Benefits of Merino Wool - Part 3, Sustainability

by Taylor McClean January 12, 2021

This week we’re wrapping up our discussion on merino wool’s benefits, and I’ve saved the best perk for last – sustainability. To understand merino wool’s sustainability, we have to look at where merino sheep fit within the carbon cycle, and the fiber’s full lifecycle assessment.

Step 1: Carbon

Think back to your science class days to remember the periodic table of elements, and maybe you’ll picture carbon in it’s little square on the second row, nestled between boron and nitrogen. That’s the carbon we’re talking about, and it’s a fundamental element of all life. Combine carbon with other elements, and it takes on a different form – for example, one carbon atom plus two oxygen atoms give us the molecule carbon dioxide (CO2), which exists naturally in our atmosphere. Carbon is also a building block in fossil fuels, proteins, carbohydrates, and many more complex macromolecules that form life.

So, carbon is everywhere, but to kick off our wool lifecycle assessment, we’ll start with the carbon in our atmosphere – carbon dioxide. Carbon dioxide naturally occurs in the atmosphere, and in fact it is essential in maintaining life on earth (just not too much of it – that leads to global warming). It’s released as a gas into the atmosphere in many ways, from our own respiration to volcanic eruptions to the burning of fossil fuels (hydrocarbons). And it hangs around in the atmosphere, until something happens to it.

Step 2: Plants

This is where plants come into the cycle. While we breathe in oxygen and breathe out carbon dioxide, plants are the exact opposite. As part of their photosynthesis, they “breathe” carbon dioxide and release oxygen. According to the International Wool Textile Organisation, plants absorb 155 billion tons of atmospheric carbon through photosynthesis each year, converting all that carbon into energy (in the form of sugar) to produce biomass (more plant material). The carbon and oxygen atoms still exist, but have been recombined with hydrogen (from water) to form new sugar molecules (for the science nerds out there, this is the Calvin cycle part of photosynthesis).

This process continues on, until the plants die (returning carbon and other nutrients to the soil), or are eaten by other organisms.

Step 3: Sheep

You can probably see where this is going now – merino sheep graze pastures, eating the plants that have sequestered carbon. At this point, though, some carbon is released back into the atmosphere as carbon dioxide from the sheep’s breath, and as methane from the sheep’s off-gassing (unfortunately, this methane production is the largest greenhouse gas contributor in the entire merino wool lifecycle). The rest of the carbon is used throughout the sheep’s body, including in the formation of its fleece coat. Working together, the sheep and plants engage in a mutually beneficial relationship – the sheep breathe in the oxygen released from plants while the plants breathe in the carbon dioxide released from the sheep; the sheep get energy by eating the plants, but at the same time the plants benefit from the sheep’s fertilizing waste.

And so this cycle continues, but only while the system is balanced. If the sheep are confined to one area and overgraze, the field becomes devoid of plants and flooded with sheep waste. A lack of food and unsanitary conditions in turn reduce the sheep population, until the whole system collapses. Thus, a large portion of merino wool’s sustainability starts with how the sheep themselves are managed. If managed correctly – mostly in rotating the sheep through free-range pastures - all parties flourish, even to the point where methane-eating bacteria thrive in the soil. The more methane-eating bacteria there are in the soil, the better, as they can offset the sheep’s methane producing gas and balance the carbon cycle.

One important side-note: when buying wool, make sure it’s mulesing-free. Though not directly related to sustainability, mulesling-free wool is critical to the welfare of sheep.

Step 4: Production

Sheep are shorn of their heavy fleeces once or twice a year. Because sheep don’t naturally shed their hair, shearing is necessary for them to stay healthy and active. Luckily for us, we can benefit from their abundant, excess hair by turning it into apparel. As with other fibers, wool goes through the same basic steps to become a garment – after shearing, the fleece fibers are graded and sorted by quality, then cleaned, spun into yarn, knitted or woven into fabric, and finally cut and sewn into a garment.

As with sheep management, the wool garments themselves are only as sustainable as the methods used to make them. Like all fibers, energy is needed to turn the wool into a garment – but the type of energy used (solar, wind, fossil fuels, etc.) make a big difference in the wool’s overall carbon impact. Choosing processes that use minimal energy also help – for example, forming a supply chain that is geographically close together minimizes the fossil fuels needed to transport the goods from farm to mill to factory to retailer.

Still, though, there are some inherent benefits to wool garment production – according to Woolmark, wool uses 18% less energy than polyester and about 70% less water than cotton to produce 100 sweaters.

Step 5: Death

Like all things, eventually a wool garment will come to the end of its life – hopefully because it was so loved and worn that it disintegrated past repair J And this is where wool really shines in its sustainability – there’s a healthy resale market for wool garments; it can be recycled into new garments; and its biodegradable, returning nutrients and carbon to the soil without contributing to microfiber pollution.

Remembering back to the first two posts in this series, merino wool is both strong and flexible, and because it has anti-odor properties, it can be washed less. This means that wool garments generally last longer than others (as long as they are properly cared for). If your wool sweater no longer suits your style, chances are it’s still in good condition for the resale market. In fact, according to Woolmark, 5% of donated clothes are made of wool, even though only wool only accounts for 1.2% of virgin fibers. Wool makes up a disproportionate share of donated clothes, which is a good thing – the more we can reuse and item, the less its carbon footprint.

Most importantly, because wool is completely natural, it can easily be biodegraded. This is important, because the microorganisms that break down materials often don’t recognize those that are manmade, so they don’t eat them. Think of it this way – microogranisms and bacteria have been around for billions of years, and have evolved to eat certain things. Manmade materials, particularly plastic, are fairly new – the organisms don’t know what to do with them, so they eat the natural materials that they’ve always eaten. And when a material can be completely biodegraded, there’s no micro-fibers still hanging around, building up in the environment. In as little as 3-4 months, wool is completely gone, broken down into its most elemental parts and returned as nutrients to the soil or ocean.

Step 6: Rebirth

At last, we’ve come full circle. When wool biodegrades, it acts as a fertilizer for plants by releasing nitrogen, sulfur, and magnesium into the soil – meaning that wool can actually help the environment. As plants continue to grow, enriched by the biodegraded wool’s nutrients, they continue to absorb carbon dioxide from the atmosphere. This helps prevent a buildup of carbon dioxide and thereby slows the rate of global warming. As sheep eat the plants, some of those same carbon atoms from the plant are sequestered and used in the sheep’s body, including in their fleeces. The fleeces are turned into garments, still holding onto the same carbon atoms. And when wool garments decompose in the soil, that carbon is still there, safely trapped in the earth instead of released back into the atmosphere. In this way, wool has the ability to help remove carbon from the atmosphere, making it one of the greatest fibers of all time.

Further reading:

https://www.nationalgeographic.org/article/sweet-secret/?utm_source=BibblioRCM_Row

https://www.woolmark.com/industry/research/wool-is-biodegradable/#:~:text=or%20microfibre%20pollution-,How%20long%20does%20wool%20take%20to%20biodegrade%3F,taken%20up%20by%20growing%20plants

https://www.woolmark.com/industry/use-wool/wool-processing/

https://www.woolmark.com/industry/sustainability/wool-farming-and-sustainable-fashion/

https://www.woolmark.com/environment/environmental-edit/

https://www.woolmark.com/industry/research/measuring-wools-environmental-footprint/

https://www.woolmark.com/environment/wool-and-microplastics/

https://iwto.org/wp-content/uploads/2020/04/26-March-AgR-Research-Case-Study.pdf

https://www.woolmark.com/globalassets/_06-new-woolmark/_industry/research/factsheets/gd2405-where-does-carbon-come-from_122.pdf

https://ecocult.com/5-surprising-reasons-love-wearing-wool/

https://iwto.org/sustainability/tbc-environmental-impacts-of-wool-textiles/