Is wool a sustainable fibre?

Updated 29 September 2023

It's Wool Week - all of October... So, not wanting to avoid the critical issues I'm addressing the biggest question of all - again. More info, more facts, more opinion.

Is wool a sustainable fibre?

Spoiler alert: I may have changed my mind. Please do tell me what you think in the Comments below. I'll publish what I can.

Google it and you could find any answer you want: Sustainable, Unsustainable, Low Carbon, High Carbon, Cruel, Kind, Polluting, Regenerative, Regressive, Progressive. 

Stakeholders on either side of the argument hide their agendas, pick their "science”, are tin-eared to opponents. Polemicists undermine mature debate and, hysterically (but, yes, there is a crisis), shift the boundaries of the argument in their favour.  What then of a sensible a debate on the sustainability of wool?

We can longer sufficient blandly state that "because it comes from sheep (or goats) that live on grass, and it readily biodegrades at the end of its life, wool is a sustainable fibre". The stakes are too high, greenwash abounds.  

The debate is broad-ranging and complex, and we can’t hope to cover it all here, but we will do our best and we promise to try to use the best available science - and show our references.  So let’s start by defining “sustainability”.

What is sustainability?

Back to school! Although the phrase “three pillars of sustainability” is common, the most helpful chart that explains how each pillar relates is a Venn diagram. So let’s say,  “three spheres of sustainability.” In either case, no one of them can function optimally without both of the others.

• Economic and Ecological sustainability combine to make people’s living conditions viable - until overwhelmed by social unrest.
• Ecological and Social sustainability combine to make people’s living conditions bearable - until they run out of money to sustain them.
• Economic and Social sustainability combine to make living conditions equitable - until the environment degrades to the point that Earth can’t sustain human life.

True sustainability is at the intersection of all three facets.

Like it or not, the British countryside, landscape and much of its society has been sculpted and shaped by sheep farming for up to four thousand years, so I would argue that, although it is currently in demise, if sheep farming were not socially sustainable, it would have died out in this country already. The UK still has over sixty different breeds - more than any other country - farmed by more than 35,000 sheep farmers on hills and lowlands.

Economic sustainability, a highly complex issue in itself, is something I hope to come back to properly in due course. Sheep farming is poorly paid and very hard work. It has been supported by government grant funding in for many years, partly because of the public goods benefits that farming provides to our countryside and to those who use and live in it. Ensuring economic resilience in agriculture in the UK is important to contributing to our sustainable development goals.

However in this piece, I am focusing on the aspect of ecological sustainability of wool and, necessarily, of sheep farming.

Alternatives to Wool

Nylon, polypropylene, cotton, viscose, hemp, bamboo… There are many other fibres to compare with wool. To compare these fibres with wool requires Lifecycle Assessments (LCA) of each fibre. Inputs into creating a wearable wool garment or wool blanket are significant but the Use Phase and End of Life Phase are also critical to assess the overall impact of a fibre. No Lifecycle Assessment (LCA) that I have found includes the factor of global pollution caused by alternative fibres i.e. the damage to the planet caused by not wearing or using wool from sheep bred for meat but wearing something else.  

Learn all about the alternatives to wool here: Wool, Synthetic Fibres, Bamboo Compared

Is wool a product or a by-product?

Except for Merino and a few breeds of sheep specially bred for wool, income derived from wool for most farmers is actually negative or at best, about 10% of the value of the sheep. Wool is a by-product of the sheep meat industry. Most sheep or goats would not exist were it not for humans needing (or wanting) to occasionally eat them. Wool and sheepskin are very low value in their raw state and for years prices achieved for shorn fleece in the UK market have barely covered the costs of necessary annual shearing, so for most farmers wool is more trouble than it is worth. Merino is a special case and I am excluding merino from this discussion.

We need to establish the sustainability credentials of the main product that wool rides on the back of - the sheep meat industry. This opens up the argument that there is an alternative (arguably healthier) source of protein and nutrition. However, no other food sources produce wool as a by-product, so immediately we find ourselves comparing apples with oranges.

Further, differing levels of sustainability pertain across different agricultural systems and again in different countries and different climates.

Although lamb/mutton compares favourably in respect of micronutrients with other foods, the science is clear that most of us should eat less red meat. I go some way to address the meat aspect of sheep farming here. 

The argument against the sustainability of wool

Farming is “the most destructive force ever to have been unleashed by humans”(!)

Polemicists assert that farming, particularly, sheep and cattle is terrible for the environment. Volumes of peer-reviewed research do support their position - that we in the gluttonous West should all eat less meat and immediately stop intensive farming. The litany of woes caused by agriculture is long and ugly. To name a three of the worst: -

• Agricultural pesticides have caused a drop in insect numbers in Europe of 75%.
• Gross overuse of antibiotics causes antibiotic-resistant bacteria - 75% of antibiotics sold in Europe are used on farm animals - and risks catastrophic consequences for global health.
• Runoff from agriculture is the biggest single polluter of rivers, responsible for 40% of damage to waterways, according to an Environment Agency reportpublished in September 2020.

Generally, sheep farms in cooler or temperate climates are more sustainable than those in warmer or drier climates. In a study of 7 European countries, the UK ranked better than average leading animal health, animal welfare and agri-environmental management spurs, all relating to higher environmental and welfare standards. It found that UK farms can be regarded as "reasonably sustainable", yet it concluded that "all farm types in all countries are facing challenges regarding their overall sustainability". This can be examined here.

Another study, however, found emissions associated with sheep meat production are linked strongly to farm type within a country. For example, sheep produced in UK lowland systems typically have lower emissions than their upland and hill counterparts. It’s pretty obvious really: the less effort put into your sheep or cattle farming, the lower carbon footprint it will have. Hill farming appears to be low intensity, but it is less efficient and requires more land per animal.

Environmental campaigner George Monbiot is part justified in his claim that “the biggest population crisis is not the growth in human numbers, but the growth in livestock numbers” i.e. the amount of burping ruminant cattle and sheep must stop rising. Many conventional agricultural practices are well proven to degrade the land, stripping the soil of life and its nutrients, causing farmers to input more intensive, carbon-costly chemical substitutes.

Disappointing for many of my readers… claims to the contrary, that we should eat more meat to save the world, are (sadly) based on flawed science and have been comprehensively disproved.  The 2019 IPPC report states that agriculture, forestry and other land uses represented 23 percent of all manmade greenhouse gas emissions worldwide from 2007 to 2016. This includes more than 40% of global methane emissions (methane being second only to CO2 as a greenhouse gas).

What Mr Monbiot would have us believe is partly right. Although his position lacks balance, proportionality and nuance, sadly the peer reviewed science is on the side of reduction of ruminant farming. In his latest polemic, which has unsurprisingly garnered much publicity for his book Regenesis, however, he eloquently blends some facts and peer-reviewed studies with extrapolated conclusions based more on commentaries and comes to a radical conclusion: if he had his way there would be no cattle, sheep or goats left on the planet, all our fields would be re-wilded and we would all get our protein from a lab-grown bacterial sludge. Farming would be finished.

I’m not against re-wilding. On the contrary, It’s already proving to be one answer to some of our environmental woes. Many areas of upland Britain support little livestock and there is room for change of use. Large scale endeavours like the 500,000 acres Afric Highlands project are inspiring and will hopefully show how nature, local communities and livelihoods can help each other thrive. We need more big initiatives like this and many smaller projects too, increasing biodiversity and supporting increased carbon sequestration. It’s also important that farming communities are supported in any transition that government chooses to lead. What I am against is plausible and eloquent journalists pulling the wool over people’s eyes and throwing all the babies out with the bathwater. (I love to mix a metaphor), but this polemicising is dangerous stuff. It’s great for headlines, publicity and selling books, but it polarises the argument. Crucially, it undermines trust in the organic movement which has been a leading force in educating people about the dangers of chemical-first high input industrial farming. The idea of turning the whole of outdoor Britain into a forest is so far-fetched it disengages moderates from the debate and is, after all, bonkers.

Methane

Ruminants produce methane by enteric fermentation and release it by burping. Methane is a short-lived but dangerously powerful greenhouse gas. Ruminants (cattle, buffalo, sheep, goats, deer) generate about a third of all global anthropogenic methane gas. These emissions tend to be higher, per unit of food output, in grazing than in mixed or landless (intensive) systems. 
For as long as livestock continue to be farmed, methane continues to exert a warming effect on the climate. As such, the argument that since methane’s impacts are temporary and they do not matter, is wrong. Its effects will be permanent until ruminant production is halted.

Fewer ruminants: less methane

Should we shift, therefore, to vegan diets? Well maybe not just yet... Grass-based ruminant systems on marginal land (land unsuitable for crop production) have been found to produce human digestible protein more efficiently than food crops.
Alternative land uses including agroforestry and feeding livestock on "leftovers" (we have far too much food crop waste) have also been conveniently ignored by our radical flanking polemicist.

A meta-analysis report on multiple studies of grazing systems and their associated methane, other greenhouse gas (GHG) emissions and soil carbon sequestration, by the Oxford Martin School, University of Oxford, agreed that the rise in livestock numbers must be reversed, but it also found that, with alterations to livestock systems, we can meet human protein demand (at a WHO recommended diet "healthy" diet rate) as part of a mixed agro-system, whilst also freeing up large areas of land for re-wilding.

Finite land supply

A world in which grazing ruminant systems were to supply all our future meat demand would be highly problematic. Such a future would require a massive expansion of grazing land, which would inevitably occur at the expense of forest cover, and a massive increase in methane emissions.

What is more, while ‘grass-fed’ animals may not be dependent on arable-based feeds, the supposition that they are using spare land that could not be used for something else is also mistaken. Our land is finite. We have already disturbed too much of it, mostly to produce food. This includes former wetlands and grasslands as well as croplands: land that is used to graze animals could potentially be used for something else – for food, for nature conservation, forests, or bioenergy. There are almost always alternatives: the question is, what do we want? 

Environmentalists generally address only one of the three spheres - Ecology - and that only from a limited perspective. They often ignore the Social facet and much so the Economic facet of Sustainability. Mr Monbiot conveniently ignores the poorly understood but enormous problem of microplastics pollution and toxification which I briefly address here and below.

Farming, it is unarguable, needs to clean up its act, and while Mr Monbiot may be on one extreme end of the argument there is much consensus that the agri-industrial methods used in the past 50 years have come at great environmental cost and are unsustainable.  The ecological sustainability question then is, assuming that we need to derive sufficient nutrition from our land, which ways of configuring land might pollute and degrade the land least and yield the most carbon sequestration for the least GHG emissions cost? And do sheep have a place in that system?

So, what is the sustainability argument for wool?

How can wool be sustainable? What do we want, Wool or Plastic?

Set against the arguments for or against sheep farming there is the significant factor of the damage caused by use of alternative fibres to wool.

Microplastic pollution

16-35% (200,000 - 500,000 tonnes) of all microplastics entering the oceans each year are from synthetic textiles.

Microplastic pollution is now one of our greatest global challenges. Around 12.2 million tonnes of plastic enter the global marine environment each year. Of this, 3.2 million tonnes are estimated to be primary microplastics, i.e. particles less than 5mm in size released directly into the environment.

A major source of microplastics is the shedding of fibres during machine washing of synthetic textiles. Through the laundry wastewater these microfibres enter marine systems where they are ingested by aquatic organisms and enter the food chain or accumulate on the ocean floor, acquiring toxins on the way.

Natural wool degrades in months whereas synthetic fibres will never biodegrade, but just keep breaking down into smaller and smaller pieces.

• Every piece of plastic ever made still exists
• Even incineration does not terminate plastic waste.
• Microplastics enter the cells of animals, interfering with cell nuclei, causing possible DNA damage
• They introduce toxins they have absorbed into animals
• They interfere with digestion and absorption of important nutrients
• They are found in breast milk, lung tissue, food and drink, farming sludge
• There might be 23 times more plastic pollution in the soil than in the sea
• Studies have shown that a 5 kg wash load of polyester fabrics can release up to 6 million microplastic fibres into the environment.

One caveat: natural fibres need to remain as “natural” as possible. Natural fibres should be dyed with Azo-free or natural dyes and should not be treated with silicon that coats them with plastic, or they will take longer to biodegrade.

Microplastics found across the Arctic could be from your laundry

We now know something of the dangers of microplastics, but are still learning, and everything we are learning points to long term damage of ecosystems and multiple species.

Life Cycle Assessment

Wool is a high performance fibre, typically lasting much longer in use as a textile product than others. As found in the first full LCA for a wool garment, the use phase has a significantly lower CO2eq than other textiles. Wool textile items last longer, are washed less frequently, so use less water and are easily repairable. They are also re-used and handed on, often through multiple owners. At end-of-life wool readily and naturally biodegrades. Cared for properly, Wool blankets and garments can last for generations. Who ever heard of a family heirloom polyester jumper?

Manmade fibre items have a far shorter use phase, need far more frequent washing as they harbour bacteria (odours) and never break down. They end up causing mountains of rubbish on distant shores and subvert developing economies.

Qualities of wool compared to other fibres

The use of the vast majority of wool, however, is a by-product of the sheep industry. Not using the wool that is already grown would have virtually no effect on the industry or the production of sheep for meat and the wool would be wasted, with other potentially toxic textiles manufactured for use instead. I have briefly looked into the sustainability of other fibres like bamboo. Bamboo can certainly be part of the solution but currently has a long way to go to live up to its claims of sustainability. and you can learn more about the unique qualities of wool here .

What do we want? 

If the goal, for example, is to use land in ways that deliver maximum environmental gain while also ensuring adequate nutrition for our global population, then several options present themselves.

We might choose, for example, to base farming systems on what animals, particularly ruminants, are ‘good’ at. They are good at recycling residues and crop by-products and making use of land that can less easily be cropped to provide us with food.

The studies reviewed suggest that this Ecological Leftovers approach to livestock production – grasslands, plus a substantial contribution from feeding monogastric (pigs, poultry) food waste – could provide a population of 9 billion with about 20 g of animal protein (from all types) per person per day – much less than current Western consumption levels and below the anticipated global average of 31 g in 2050, but a useful amount.

Another strategy might be to prioritise biodiversity to graze animals in ways and only in locations where they actively foster or protect biodiversity.

Sheep feeding in an English Silvopasture

Agroforestry, a Solution?

Agroforestry is a land management approach that combines trees and shrubs with crop and livestock farming systems. It delivers a multitude of benefits both for the farm and for nature and is a very old practice, though one which has sadly been almost entirely lost from our landscape. In contrast to the prevailing mindset around trees and food production, which largely sees these two land uses as mutually exclusive, agroforestry systems are designed in a way that provides benefits to both enterprises whilst generating a range of environmental gains such as improved soil health, reduced runoff, increased biodiversity – and of course, carbon sequestration. Sheep agroforestry has even been seen to fight forest fires.

A combination of adjustments to land use, and alterations in ruminants' diet to include (healthy) food waste can, as the graph below shows, operate within an agri-system with emissions of 80% below 1990's levels, whilst sequestering carbon and releasing land for nature.

Alternative livestock futures: implications for land use from Röös et al. (2016)

The graph above looks at how arable and overall land requirements vary under the different dietary variants. It shows that both arable and total land use requirements are lowest under the meat-free (PBE and AMD) scenarios with Ecological Leftovers HD close behind.


HD = WHO "Healthy Diet", PD = Projected Diet: Projected quantities of meat and other foods follow a BAU increase to 2050. BAU = Business As Usual, meaning we don't make any changes to current agri-systems or projected dietary intake.
Source Röös et al (2016), with thanks to Food Climate Research Network (FCRN) Oxford Martin School, University of Oxford.

Discussion

Farming

Rearing sheep in various systems both positively and negatively affects people, society, the economy, and other aspects of the environment, as well as the animals themselves in many ways. Pathways linking sheep production and consumption to human food security and nutritional status, to the spread of zoonotic diseases, to jobs, livelihoods, human development and power relations between genders are highly complex.

Sheep farming for meat, milk and wool consumption plays important if differing roles in different societies and cultures.
There are also a whole host of environmental issues to consider – including the effects of animal production on biodiversity, water cycling and use.

Any one of these issues is enormous in itself and the subject of multiple contestations and debates.


Some evidence exists suggesting that, in some cases, grassland can store more carbon than forests. Thus, keeping ruminants on the land can achieve greater sequestration than removing them altogether and allowing woody vegetation to encroach.

Well-managed grazing systems can aid the process of soil carbon sequestration. Indeed, in some regions, quite high levels of sequestration are possible for a few years or decades, (giving rise to some extravagant and unrealistic claims).

Modify Behaviours

Reduce, Reuse, Repair, Reuse, Recycle

We can often change our habits around all our textile items: -

• reducing use of synthetics,
• keeping and caring for our items longer and better.
• Ensuring  we buy better quality that lasts longer
• Repairing, reusing and passing on
• Downcycle and then recycle

Many wool items can be used in a second or third life where manmade fibres items cannot be and other products are bought for the purpose.

Any wool grown should be used where possible. Usable wool that is burnt or buried is a shameful waste. The qualities of wool not shared by other fibres are huge.

Conclusions

Some land currently allocated to sheep farming could be reallocated for re-wilding for increased biodiversity, but farming systems can also adapt to provide ruminants with diets including ecological leftovers. Agro-forestry farming systems need more adoption and analysis. As with all other industries, many improvements can be made to sheep farming systems to reduce their environmental impact.

Wool textile products last well and are highly valued items, being replaced infrequently and generally made from a by-product. So, until sheep are farmed only for their wool, rather than their meat, wool is most definitely a sustainable product. While sheep are still growing wool, we need to keep using it. One might even argue we have a duty to.  Taking into account the extraordinarily damaging and long-lasting toxic effects of microplastic fibres on our ecosystems so many of which come from synthetic clothing and furnishings. It is far more sustainable than the alternatives.

I would add - as if it needs saying - that buying and eating local, British bred, mutton or lamb will always be better for the environment. Support our farmers - they need it!

 

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For Sarah and me, it has always been important to feel that we are part of the solution rather than the problem, that we are as far as possible "doing the right thing".

Since 2006 we have evangelised on the qualities of the technical wonder that is wool, be it sheep, goat or camel. It is truly Mother Nature's genuine high-performance fibre. But we need to be confident that in doing so, we are not undermining Mother Nature herself. We need our business to be sustainable (across all the spheres). We will keep following the science to inform our direction of travel and try to share our knowledge in a helpful constructive manner. I hope this has been of some interest.


You may be interested to read our previous blog posts about this subject, but the science and arguments keep moving forward so we will keep discussing this at The Wool Company and at some point we will organise the blog posts into a more digestible format.

If you've managed to read this far you may be interested in reading further on the subject. If so I can suggest the following: -

Grazed and Confused?

IWTO Sustainability main page

Environmental impacts associated with the production, use, and end-of-life of a woollen garment

Sustainability Assessment of Goat and Sheep Farms: A Comparison between European Countries

The carbon footprint of UK sheep production: current knowledge and opportunities for reduction in temperate zones

Monbiotic Man

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Other references

Many references are linked within the text above. Other references include: -

Schader, C., Muller, A., El-Hage Scialabba, N., Hecht, J., Isensee, A., Erb, K.-H., Smith, P., Makkar, H.P.S., Klocke, K., Leiber, F., Schwegler, P., Stolze, M. and Niggli, U. (2015). Impacts of feeding less food- competing feedstuffs to livestock on global food system sustainability, Journal of the Royal Society Interface, 12(113).

 Van Zanten, H.H.E., Meerburg, B.G., Bikker, P., Herrero, M. and De Boer, I.J.M. (2016). Opinion paper: The role of livestock in a sustainable diet: a land-use perspective. Animal, 10, pp. 547–549.

Röös, E., Bajželj, B., Smith, P., Patel, M., Little, D. and Garnett, T. (2016). Protein futures for Western Europe: potential land use and climate impacts in 2050. Reg Environ Change doi:10.1007/s10113-016- 1013-4.

Röös, E., Bajželj, B., Smith, P., Patel, M., Little, D. and Garnett, T. (2017). Greedy or needy? Land use and climate impacts of food in 2050 under different potential livestock futures. Global Environmental Change. 47:1-12. 

Bajželj, B., Richards, K.S., Allwood, J.M., Smith, P., Dennis, J.S., Curmi, E. and Gilligan, C.A. (2014). Importance of food-demand management for climate mitigation. Nature Climate Change, 4, pp. 924-929 doi:10.1038/nclimate2353, which in turn are based on a composite of recommendations from the World Health Organisation, the Harvard Medical School and the American Medical Association.

Eunomia (2016). Plastics in the Marine Environment. Eunomia Research & Consulting Ltd, Bristol UK, June 2016. https://www.eunomia.co.uk/reports-tools/plastics-in-the-marine-environment/ Brown R.M. (1994).

The Microbial Degradation of Wool in the Marine Environment. Thesis for the degree of Master of Science in Microbiology, University of Canterbury, New Zealand. Zhao, S., Zhu, L., Li, D., 2016.

Microscopic anthropogenic litter in terrestrial birds from Shanghai, China: not only plastic but also natural fibers. Sci. Total Environ. 550, 1110–1115. https://doi.org/10.1016/j.scitotenv.2016.01.112 NOAA (2007).

NOAA 101 Clean Guide. National Oceanic and Atmospheric Administration Marine Debris Program, US Department of Commerce  Ocean Conservancy & NOAA (2013). Talking Trash & Taking Action. Publication of the Talking Trash & Taking Action Educational Program of the Ocean Conservancy and National Oceanic and Atmospheric Administration Marine Debris Program https://marinedebris.noaa.gov/talking-trash-and-taking-action

Wiedemann, S., Biggs, L., Nebel, B. et al. Environmental impacts associated with the production, use, and end-of-life of a woollen garment. Int J Life Cycle Assess 25, 1486–1499 (2020). https://doi.org/10.1007/s11367-020-01766-0