The carbon cost of our leather goods, calculated
This article was originally published on Plant Based News under the title ‘Faux Fears Over Vegan Leather’. It is co-authored by Emma Hakansson, Collective Fashion Justice founder, and Joshua Katcher, author of Fashion Animals, and Collective Fashion Justice board member. Since publication, the above infographic has been updated to amend an error.
The leather industry’s toll on climate and biodiversity are far worse than commonly thought. Using the leather industry’s own data we've calculated how much greenhouse gas is tied to your leather bag, and it’s not looking good.
One of the most respected tools used to assess and track the sustainability of fashion materials, the Higg Materials Sustainability Index (MSI), has come under pressure recently by powerful leather industry forces.
Thirteen international leather industry trade groups signed a letter demanding that the Sustainable Apparel Coalition (who develops the MSI) suspend a bad score for leather over claims of ‘inappropriate methodologies and out of date, unrepresentative, inaccurate and incomplete data… [which] has led to a negative perception of leather.’
The SAC, whose data shows cow skin leather as the third most environmentally impactful material to produce from cradle-to-gate, after only silk fabric and alpaca wool fabric, clapped back with a public response outlining the integrity of their work and defending the data they source and methodologies they use, which they continue to refine.
One of the biggest fantasies that the leather letter tried to assert is: “Leather manufacture takes a waste from another industry and transforms it into a durable, versatile and sustainable product.”
Marketing leather as a sustainable by-product that outperforms leather alternatives has resulted in widely-held misconceptions among fashion professionals and consumers alike.
This sort of disinformation is compounded by efforts like the industry-funded Leather Naturally organization, which refers to any use of leather as ‘recycling‘ and relies on shifting the focus away from things like staggering climate and biodiversity impacts to things like plastic.
Leather is not a by-product
Leather is not a recycling charity any more than plastics are recycled from the waste of crude oil refineries.
For those who believe leather to be a mere by-product of the meat and dairy industries, and so who discount any environmental impact of leather unrelated to leather processing and tanning, let’s address that.
A by-product becomes a co-product when this secondary good – skins, from industries focused on flesh or milk – becomes desirable and profitable. Leather is a profit-driven industry set to reach a staggering $629.95 billion market size worth by 2025. It must be viewed as a co-product.
So what share of the environmental and climate impacts should the leather industry specifically be responsible for? And should they be allowed to dictate that?
The Leather Panel, part of the United Nations Industrial Development Organization argues that the cattle and ‘livestock’ industry would not be affected if leather sales stopped completely.
It uses this claim to argue animal husbandry is not related to the leather industry, so greenhouse gas emissions from it should not be included.
This is a flawed argument. The meat industry and slaughterhouses specifically have reported their multi-million dollar losses when skins are not selling or selling for far less, often accounting this to the rise of leather alternatives.
At the very least, the leather industry can be considered a great subsidy to beef and dairy industries. In the dairy industry, only female cows, who can become pregnant and so produce milk, are valuable alive.
Because of this, countless newborn male calves are slaughtered annually since they won’t be producing milk. These newborn calves provide ‘valuable hides for leather‘ and without the sale of their skins, particularly due to the decline of veal consumption, the dairy industry loses a lot of income.
For these reasons, and for the fact that there is no animal leather without animal farming, we’re compelled to include the greenhouse gas emissions associated with animal farming in the leather supply chain.
A failure to do so is a failure to account for all relevant data. That’s why the SAC has expressed a need to include ‘livestock rearing practices’ as well as ‘economic allocation factors’ in consideration of the complexities of bovine leather supply chains. This is precisely why the leather industry has come out strongly against the SAC’s Higg Materials Sustainability Index, because it challenges the core of its carefully marketed claim that leather – an intensive livestock product with massive impacts – is somehow ‘natural’ and ‘sustainable’.
If the leather industry had it their way, it would evade responsibility for anything upstream of tanning, and then some.
Leather’s assault on innovation
There are currently efforts by the German Leather Federation to ban the use of the word ‘leather’ in synthetics and plant-based alternatives.
With high-tech and pioneering materials like lab-grown leather, mycelium (mushroom) leather, apple, pineapple, and cactus leather, bioplastic leather, and countless other emerging materials cropping up all over the world, the leather industry is attempting to stomp out threats to its bottom line.
But the industry’s assault on innovation is nothing new. A 1915 article in the Shoe and Leather Reporter entitled Artificial Leather a Misnomer and a Fallacy railed against attempts at replacing leather with synthetic or plant-based innovations of that era like oilcloth and gutta-percha.
Leather industry leader James B. Reilly, who penned the article said: “Leather manufacturers purpose to stand by no longer and withstand the defamation cast upon the reputation and character of genuine leather by would-so-calleders of so called artificial leather.
“Leather is the skin of an animal… Nothing else is leather, and nothing else can honestly be called leather.”
The climate impact of animal and faux leather
To make the strongest case, we started by erring on the conservative side and assumed the leather industry’s claim of 0 percent impact for anything occurring before tanning the hides.
We can compare the greenhouse gas emissions of the most common faux leather, polyurethane ‘leather’, with cow skin leather emissions, barring those emitted on farms or grazing land.
When we use the leather industry’s own shared data for this and all our arguments, it still does not fare well for them.
The Leather Panel has shared a study that begins counting emissions after the slaughterhouse section of the leather supply chain. Included emissions here are energy use in tanneries, chemical outputs and their emissions, transportation, and so on.
In this case, CO2e emissions (emissions of various gasses translated to the common unit of carbon) for leather equal 17.0kg of CO2e per square meter of leather produced. In comparison, artificial leather’s total supply chain has an impact of 15.8kg of CO2e per square meter.
As you can see, even allowing the leather industry’s unreasonable assumption of no impact from animal farming, faux leather’s entire life cycle produces fewer emissions.
Leather Panel’s shared study chooses to include end-of-life incineration in the impact of faux leather. It’s illogical to include incineration for synthetics but not for animal leather, and while faux leather won’t effectively biodegrade, neither will animal-derived leather to the point of total decomposition – even in controlled climate study conditions shared by leather tannery groups.
In an accurate comparison, synthetic leather would have even fewer emissions than cow skin leather.
Elsewhere in its report, the Leather Panel shares an impact estimate which includes farm emissions – this is a fairer estimate of leather’s impact, and again comes from its own reporting.
Here, the carbon footprint of cow skin leather is found to be 110.0kg of CO2e per square meter, making cow skin leather nearly seven times more climate impactful than synthetic leather by the square meter.
The carbon cost of leather
So how many kilograms of CO2e are in our leather jackets, bags, and shoes?
After asking creators of these products how much leather is required for them, we have all the numbers we need to work this out.
By multiplying the CO2e/m2 emissions of both faux and cow skin leather respectively, with the material requirements for each product, we see exactly how our fashion choices contribute to the climate crisis.
If you’re someone who has heard that vegan leather is worse for the environment, or if you’re interested in the ongoing safety of the ecological world, these calculations may be worth your consideration when next designing or buying these goods.
Bag leather requirements from e-mail correspondence with Sans Beast (0.914m2), shoe leather requirements averaged from data from Russell Moccasin Co, as well as Willy Moc Handcrafted Shoes (boots 5-8sq ft, shoes 3-5 sq ft, averaged and converted to m2), jacket leather requirements based on e-mail correspondence with Moore & Giles Inc (10-15sq ft, averaged and converted to m2).
‘Would you rather the skins were just tossed into landfill?’ This is a common question that both the leather industry and sustainable fashion community often pose.
Based on the data, our answer is yes, and here’s why: throwing a cowhide in the garbage has a smaller climate impact than turning it into leather.
Yes, the carbon that is biologically stored in untanned cowhides if sent to landfill would produce some methane emissions as they rotted, but it’s nowhere near as much C02e created when we chemically transform those skins into leather (which will eventually be discarded or incinerated anyway).
This holds true even when we factor in the footprint of a synthetic alternative assuming someone may opt for that instead. In fact, just the processing and tanning of raw skins into leather is about as impactful as producing faux leather itself.
Why not use the material which does not financially contribute to slaughter then? For the sustainable fashion community that is rightfully concerned with waste, this is quite counterintuitive. Why we should throw something away instead of using it, is a tough sell.
These comparisons are startling and ring true to the reality that how we consume fashion, as well as design and produce it, has a major impact on the environment, especially the climate crisis.
Of course, this is not as in-depth as a full life-cycle assessment, but the data is poignant, verified, and crucial to consider. Although leading voices in sustainable fashion continue to justify and rationalize leather, this is mostly due to very effective PR from the leather industry and its gospel about what is natural, genuine, real, and authentic.
The marketing hype behind leather, even the rare vegetable tanned leather, simply cannot stand up against fact-driven analysis which shows animals do not belong in responsible fashion supply chains.
And It doesn’t end with carbon, either. When it comes to biodiversity, water, land use and deforestation, toxic eutrophication and more, leather should quickly be relegated to the rank of fashion’s worst threat to the environment.
Data for landfill equations
Is the impact of sending hides to landfill worse or better than the impact of using hides to turn them into leather? (Sources below)
Total emissions from sending unprocessed hides to landfill (in kg of CO2e / m2 of hide)
= Total emissions from turning hides into leather – Emissions from leather processing + Emissions in landfill
= 110 – 17 + 1.152
= 94.152 kg of CO2e / m2 of unprocessed hide in landfill
Total emissions from turning hides into leather = 110kg of CO2e / m2 (Source: Leather Panel)
Difference in emissions (i.e., leather – landfill)
= Total emissions from turning hides into leather – Total emissions from sending unprocessed hides to landfill
= 110 – 94.152
= 15.848 kg of CO2e / m2
Additional sources and calculations:
Emissions from leather processing = 17kg of CO2e / m2 (Source: Leather Panel)
Emissions in landfill
= CO2 emissions per square metre of hide x methane-carbon mass ratio
=CO2 per tonne of hide / Hides per tonne X Hides per square meter X Methane-carbon mass ratio
= 1.152 kg of CO2e / m2
CO2 per tonne of hide in landfill
624kg of CO2 is emitted per tonne 1000 kg of putrefied hides (Source: Leather Panel).
Hides per tonne
An average cow hide weighs 6.1kg (Source: UNESCO).
1000 / 6.1 = 163.93 hides per tonne.
Hides per square metre
An average cow hide is 47.5 square feet or 4.41 square metres (Source: Leather Hide Store)
= 1 hide per 4.41 square metres
Methane-carbon mass ratio
In order to turn data which refers only to carbon into data which is aligned with the rest of our data — measured in CO2 equivalent emissions — we need to account for how carbon would turn into methane in the process of breaking down in landfill (Source: U.S. Environmental Protection Agency). Methane and carbon have different atomic masses, 16 and 12 respectively (Source: National Library of Medicine: Methane; Carbon).
* The sources and calculations in this piece were verified by the experts at Faunalytics, a non-profit research organization that provides data and resources to support effective, evidence-based animal advocacy.