WOOL FACTSWOOL ANDTHE CARBON CYCLEWOOL IS MADEFROM ATMOSPHERICCARBON
Carbon is a vital building block for lifeand for many of the products we use
every day. Many textiles and fibres are
made from carbon-based products, but
only some, such as wool, are made fromatmospheric carbon. In addition, wool
is naturally biodegradable. Whendisposed of, wool acts like a fertiliser
by slowly releasing valuable nutrientsand carbon back into the soil.
By comparison, the carbon in themajor synthetic apparel fibres, such aspolyester or acrylic, is extracted fromfossil fuels, de-sequestering carbon
stored millions of years ago.

Pasture
eaten bysheep

Pastures areregenerated

Wool
converted toclothing

CARBON CYCLE
IN WOOL
Garments canbe reusedor recycled

Recycled
products canbe composted
and returnedto the soil

PHOTOSYNTHESIS IN THE WOOL CYCLE
CO2 EMISSIONSPHOTOSYNTHESISPLANTRESPIRATIONANIMAL RESPIRATION
CO2+CH4PASTURE
CONSUMPTIONWATERORGANIC CARBON

WOOL’S CARBON
IS NATURALOXYGENDEAD ORGANISMS AND WASTE PRODUCTS

Organic carbon makes up 50% of the weight of wool, which is morethan cotton (40%), and wood pulp-based fibres, such as rayon,
viscose and bamboo (42%). The carbon in wool is derived from thedigestion of plant material by sheep. Wool, especially Australianwool, is produced in extensive pasture systems, where the dietis dominated by grasses and other pasture plants. These plants
capture carbon from the atmosphere and convert it into organic
compounds through photosynthesis (which supports much of the lifeon earth). This means that most of the carbon contained in freshly
shorn wool was only removed from the atmosphere during theprevious 1-2 years, and is part of a natural, renewable system.

WOOL AND THE CARBON CYCLE

THE IMPORTANCE OF WOOLFOR THE CARBON CYCLE
Wool is a short-term store of atmospheric carbon, sequestered ina resilient, wearable form for the life of the garment. By storing thegreenhouse gas carbon dioxide (CO2), wool prevents the stored gas
from contributing to climate change for the time the garment is in use.
Converted into carbon dioxide equivalents (CO2-e), 1 kg of clean wool
equates to 1.8 kg of CO2-e. Extending this concept, the 2016/17 Australianwool clip represents more than 419 million kg of CO2-e in clean wool.
All this CO2 is removed from the atmosphere for the fibre's life – fromwhen grown on the sheep, through the wool product's use phase – until
it is disposed of and biodegrades. For many wool garments, this period isgreatly extended because wool is used or recycled in a variety of textiles(e.g. carpet and furnishings), which arguably have a longer useful life
than many wool garments. Wool is the most reused and recycled fibreof the major apparel fibres and can be converted into new long-lastingproducts, such as garments, mattresses and upholstery. Even thoughwool represents only 1.2% of the virgin fibre supply, surveys have shown it
represents about 5% of clothing donated to charity.

WHAT HAPPENS NEXT: WHERE DOES
THE CARBON IN WOOL GO?
In addition to being part of the natural carbon cycle, at the end of its
life wool breaks down naturally and returns to the soil, rather thanaccumulating in landfill, as is the case with synthetics. Because wool iscomposed of a biodegradable natural protein (similar to that of humanhair), when disposed of, it acts like a fertiliser by slowly releasing
valuable nutrients and carbon back into the soil. By contrast, synthetic
fibres, such as polyester and acrylic, are derived from fuels and part ofa non-renewable system. These man-made fibres are not biodegradable
and contribute significantly to landfill.

WOOL IS BIODEGRADABLE
Wool biodegrades readily in as little as three to four months,
but the rate varies with soil type and conditions, climate
and wool characteristics. Some studies found more rapiddegradation after only four weeks’ burial. This process releases
essential elements such as nitrogen, sulphur and carbon backto the soil, where they are taken up by growing plants.
Research has shown that processing treatments, such as
dyeing and anti-shrink treatments, can affect the rate ofbiodegradation in soil, causing an increase in the initialresistance of wool fabric to degradation. However, this is a
short-term effect, typically not persisting beyond eight weeks.
See the fact sheet Wool is biodegradable for more information.

After being buried for six months, the nylon jersey fabric (left)
remains relatively unchanged, whereas the wool jersey fabric (right)
has significantly biodegraded.

WOOL AND THE CARBON CYCLEREFERENCES
Wool biodegrades readily in as little as three to fourmonths but the rate varies with soil, climate and wool
characteristics:

440950, 2018, p.1.

– Hodgson A., Collie S. (December 2014). Biodegradabilityof Wool: Soil Burial Biodegradation. Presented at 43rd
Textile Research Symposium in Christchurch – AWIClient Report.

– Hawkesworth, A., Australasian Sheep and Wool: A
Practical and Theoretical Treatise: From Paddock toLoom. From Shearing Shed to Textile Factory, 1948: p. 91.

This releases essential elements such as nitrogen,sulphur and magnesium back to the soil, able to be taken
up by growing plants:– McNeil et al. (2007). Closed-loop wool carpet recycling.
Resources, conservation & recycling 51: 220-4.
Converted into carbon dioxide equivalents (CO2-e), 1 kgof clean wool equates to 1.8 kilograms of CO2-e: 1 atomof carbon representing 27.3% of the molecular weightof CO2 (1 x C atom (mwt 12) + 2 x O atoms (mwt 2 x 16 =32) – hence 12/(12+32) = 12/44 = 0.273). Hence, to derive
the CO2 equivalence of 1 kg of clean wool, multiply 1 kg ofclean wool by 0.5 to convert to pure carbon, then divide by
0.273 to convert to CO2 equivalents.
Of the major apparel fibres wool is the most reusable
and recyclable fibre on the planet: Russell SJ et al.
Review of wool recycling and reuse. Proceedings of 2ndInternational Conference on Natural Fibers, 2015, 4.
Organic carbon makes up 50% of the weight of wool:– Simmonds, D. Proceedings of the International WoolTextile Research Conference, International Wool Textile
Research Conference. Melbourne, Australia: CSIRO
Publishing, 1956, C65.
– Hawkesworth, A., Australasian Sheep and Wool: A
Practical and Theoretical Treatise: From Paddock toLoom. From Shearing Shed to Textile Factory, 1948: p. 91.
– von Bergen, W., Wool Handbook: A Text and ReferenceBook for the Entire Wool Industry. Vol. 1. 1963, New York:John Wiley and Sons Inc. 315-450.
– Causarano, H.J., et al., Soil organic carbon sequestrationin cotton production systems of the southeastern UnitedStates. Journal of Environmental Quality, 2006. 35(4): p.
1374-1383.
Organic carbon makes up 40% of the weight of cotton:
Casuarano, H.J, Franzluebbers, A.J., Reeves, D.W, Shaw,J.N. (2006), Journal of Environmental Quality, 35, 1374-1383.
Organic carbon makes up about 42% of the weight ofwood pulp-based fibres like viscose: Viscose C18H32O16
is a polymer of sodium cellulose xanthate, produced byreacting cellulose with alkali and carbon disulphide:Open Chemistry Database, Compound Summary for CID

WOOLMARK.COM© October 2023 The Woolmark Company Pty Ltd. All rights reserved.

The 2016/17 Australian wool clip represents more than419 million kilograms of CO2-e in the clean wool:– AWTA Key Test Data, 2016-17.
Wool is the most reused and recyclable fibre of the major
apparel fibres: Russell SJ et al. Review of wool recycling
and reuse. Proceedings of 2nd International Conference
on Natural Fibers, 2015, 4s.
Even though wool represents only 1.2% of the virgin fibre
supply, surveys have shown it represents about 5% ofclothing donated to charity:– Y Chang, H. L Chen, and S Francis, Market Applications
for Recycled Postconsumer Fibres Family and Consumer
Science 1999. 27(3): p. 320.
– G. D. Ward, A. D. Hewitt, and S. J. Russell, Proceedingsof the ICE. Fibre composition of donated post-consumer
clothing in the UK. 2012 166(1): p. 31.
– Red Book 2016: Long term global supply/demand update.
PCI Wood Mackenzie.
Polyester, acrylic and nylon are all produced fromhydrocarbons or propylene derived directly from fossil
fuels, and are therefore part of a non-renewable cycle.
These fibres are also non-biodegradable:– Russell, I., Combined insect-resist and rot resist
treatments of wool insulation. 1992, CSIRO Division ofWool Technology: Australia.
– Szostak-Kotowa, J., Biodeterioration of textiles
International biodeterioration & biodegradation, 2004.
53(3): p. 165-170.
Some studies found more rapid degradation with marked
weight loss after only four weeks’ burial in soils: (HodgsonA, Leighs SJ, van Koten C. Compostability of wool textiles
by soil burial. Textile Research Journal. 2023;93(1516):3692-3702.
Results demonstrate that chemical processing of woolfabrics does impact on the rate of biodegradation (as aresult of soil burial). The short-term impact is generallythat of an increase in the fabric’s initial resistance todegradation, rather than an increase in susceptibility:– (Hodgson A, Leighs SJ, van Koten C. Compostabilityof wool textiles by soil burial. Textile Research
Journal. 2023;93(15-16):3692-3702