The real carbon footprint of leather

The real carbon footprint of leather

Determining the carbon footprint of products and production is a necessity and requires a thorough understanding of what a carbon footprint actually is and which complexities surround it. The carbon footprint of the food industry, from which leather is sourced, is already complex, and difficulties also arise when allocating the impact of leather to separate processes. Despite what we know about environmental management and best practice in leather manufacture, the knowledge we have on assessing a carbon footprint, and the answer to any question surrounding the real carbon footprint of leather is still tentative, at best.

One standard for CO2 allocation
Measuring the CO2 impact of leather has been an industry-wide goal, requiring a set standard. COTANCE, Confederation of National Associations of Tanners and Dressers of the European Community, formulated the first set of guidelines, which resulted in the first Product Environmental Footprint Category Rules (PEFCR) for leather. These rules provide a foundation and signify the first unified approach for measuring the CO2 impact of leather, based on a set standard. The PEFCR enables the industry to establish a method to assess the leather life cycle; the next step towards a global tool for assessing leather impact.

Allocating the livestock carbon dioxide equivalent
Allocating the carbon footprint of livestock remains the biggest challenge. Although leather is a by-product of the meat industry (according to the PEFCR standards), there is now an ongoing demand to consider the whole-life impacts of the material when determining the carbon footprint. (De Rosa et al., 2018).

The PEFCR specify the percentage of CO2-e allocation for each type of leather. For example, the carbon dioxide equivalent of animal farming that allocated to full-grain bovine hides is estimated from 2.7 to 5.39 kg CO2-e /m2. This amount differs for split leather, where 1.88 to 3.76 kg CO2-e /m2 is transferred for the grain side (grain split), and 0.82 to 1.63 kg CO2-e /m2 is attributed to the flesh split (the flesh side of the hide, often used for suede).

These examples highlight the difficulty in mapping carbon footprints of products for an industry with a variety of resource materials and production methods, as well as emission and waste management exist. No consensus has been reached on the definite way to measure the leather footprint, and it is unlikely that an easy answer will be found soon.

The full footprint
Much effort has been made to establish the carbon footprint of leather, however, there is still no established method. Leather can be produced using various resources and processes, and the final footprint is even influenced by location. One approach could be to look at the processes separately, and divide each process into ‘upstream’, ‘core’ and ‘downstream’ processes (Brugnoli & Kràl, 2012), depending on where each process is in the supply chain. The work of Jutta Knödler (2012) formed a baseline for solving the footprint of leather. Knödler established a framework for a comparative approach, by allocating a large amount of CO2-e to cattle rearing (something that is since disputed). The overall footprint from ‘cradle to grave’, was subsequently calculated by including the CO2-e of lifetime use into the allocation. 

Longevity and biodegradability are still absent from the carbon footprint equation. These factors can make a profound difference when leather is compared to polyester or textile products. Not only does leather last longer in general, but it is also reusable and biodegrading, and therefore doesn’t need to be disposed of. The leather industry has also recently challenged the Sustainable Apparel Coalition (SAC) on the Higg Index score applied to leather. The Higg Index is used to assess the sustainability of materials and was criticized by the leather industry for not considering many factors. Industry experts are now working together on better standards.

Although there are a lot of aspects in Knödlers framework up for debate, the framework provides a basic approach to examine the full footprint of a material. Brugnoli also presented another leading view in the creation of a framework, specifying that it is important to also look beyond the downstream impact at end-of-life, which is different for leather than plastics. One of the most revolutionary insights on the impact of leather production was provided by Dr Mitloehner, a professor and air quality extension specialist. Mitloehner hypothesized that the methane emission cycle from cattle is consistent and, therefore, the CO2 impact of cattle remains zero. The CO2-e calculation demonstrates there is no impact as long as the size of the cattle herd remains consistent or decreases. Superimposing this hypothesis on the numbers suggested by Knödler yields an even smaller carbon footprint.

What is still missing?
There are still many uncertainties surrounding the calculation of leather carbon footprint. Many hypotheses are contradictory, and a struggle about allocation hardly serves a progressive approach to the issue. An example is the issue regarding methane versus CO2-e. Methane remains in the atmosphere for ten years, whereas CO2 lasts for hundreds of years. Dr Mitloehner suggests that this may level out the impact of cattle. Furthermore, the emergence of regenerative farming (Stocks, 2019) implies cattle rearing may create a positive impact on the carbon footprint. How will we apply this to leather?

According to a calculation by the ECO2L certification scheme, the continuous improvement in tanning methods has enabled a reduction of the average tannery footprint. The animal feed itself also has the potential to cut the methane emissions from cows by half (Wallace et al. 2019). Being able to include the individual elements of a leather value chain such as the feed regime, region, and product longevity in a measurement framework could bring interesting new insights to how we measure material sustainability.

References

  • Allen, M. R. et al. (2018). A solution to the misrepresentations of CO2-equivalent emissions of short-lived climate pollutants under ambitious mitigation. Retrieved from: Climate and Atmospheric Science. [Accessed: 20 October 2020] 
  • Brugnoli, F., Král, I. (2012) Life Cycle Assessment, Carbon Footprint in Leather Processing. Unido. Retrieved from: Leatherpanel. [Accessed: 20 October 2020]
  • Stocks, C. (2019, June) The truth about farming and climate change, Farm Business, Issue 68. Accessed at: Farm Business. [Accessed: 20 February 2020]
  • De Rosa-Giglio P., Fontanella A., Gonzalez-Quijano G., Ioannidis I., Nucci B., Brugnoli F. 2018. Product environmental category rules – Leather. European Commission. Available at: European Union. [Accessed: 20 February 2020] , 
  • Flowers, K.B. and Flowers, I. 2018. Levelling the playing field. International Leather Maker May/Jun. p. 28-31
  • Knödler, J. (2012) Sustainability Benchmarking – the carbon footprint of upholstery materials for car seats. Available at: VÖLT. [Accessed 9 April 2018]
  • Mitloehner, F. M. (2016) Livestock’s Contribution to Climate Change: Facts and Fiction. Retrieved from: University of California. [Accessed 20 October 2020]
  • SAC (2020) SAC Responds to Leather Industry Concerns Over Higg MSI. Retrieved from: Sustainable Apparel Coalition. [Accessed: 20 October 2020]
  • Wallace, et al. (2019) A heritable subset of the core rumen microbiome dictates dairy cow productivity and emissions. Science Advances. Retrieved from: ScienceMag [Accessed 22 April 2020]