The world's trusted guide to sustainable and ethical fashion

The world's trusted guide to sustainable and ethical fashion

Higg Says Natural Fibers Are Worse for the Environment than Synthetics. Is That True?

a small herd of alpaca wandering across a dirt road looks curiously at the camera

When PETA released its footage of what they deemed alpaca abuse at a large farm in Peru, the advocacy organization included in its statement that alpaca is rated as “the second most environmentally damaging material after silk.”

PETA is always an extreme example. (Apparently, they’ve never tried taking their nervous cat or dog to the vet. “In shocking footage, cat vomits in carrier on the way to the vet! Authorities call for investigation!”) But in this particular case, when it comes to alpaca’s sustainability rating, they’re not wrong. Technically.

The issue here is the Higg Index, the technology platform that shares environmental fashion data from the Sustainable Apparel Coalition (SAC). It visually ranks the environmental impact of various materials used in fashion. And it has become the go-to data platform for brands of all sizes — from Allbirds to Eileen Fisher to H&M — who are trying to measure and reduce their environmental impact. 

Higg and the SAC seem to have it out for natural materials. Seven of the ten “worst” textiles with the biggest impact are natural, including silk, alpaca, cotton, hemp, flax (linen), wool, and jute, in that order. Acetate and modal, which are semi-synthetic plant-based fibers, come in at sixth and ninth worst, respectively. Meanwhile, most of the ten “best” fabrics, or the ones with the lowest impact, are synthetic, including aramid, elastane, polylactic acid fibers, polyester, polyurethane, nylon, and acrylic. 

So, according to Higg, silk (total impact of 1086) has almost 14 times the impact of its semi-synthetic and cheaper replacement, acetate (79.6). Apparently, you could cut the negative impact of an alpaca sweater (320) by 85% by replacing it with acrylic, at 48.7. It might not feel great to know your dollars are going to a factory owner instead of an indigenous herder, but at least you’re saving the environment?

Similarly, if you wanted to reduce the impact of that artisan-made goat leather knapsack from Ethiopia (148), you could instead import polyurethane (37.2) from China, and give that to the leather workers. Of course, then that goat hide, a byproduct of the local cuisine, would be thrown in the landfill. But now your environmental impact is lower, and also PETA will leave you alone. It’s a win-win for brands, if a very bizarre move for the artisans.

Or, you could make that cotton (101) sundress for cheaper with polyester (36.2) and call the dress sustainable.

I’m not the only one who has remarked upon this unintuitive ranking. Experts fear that Higg’s data and labels could drive brands and consumers even further away from natural fibers and the farmers that make a living on them, and toward man-made fibers like rayon, polyester, and acrylic. 

So what is going on here? Are natural fibers really worse for the environment? Let’s find out. 

Higg Defines Sustainability Narrowly

“We have to agree on how we calculate,” says Sandra Roos, a textiles researcher and expert on life cycle analyses who recently joined the team of the Swedish brand KappAhl. “Otherwise everyone could calculate differently. But sometimes the rules don’t really fit the question.” 

The Higg Index was created to answer a seemingly simple question: what materials have the smallest negative impact on the environment? But answering can be complicated. You’re comparing apples to oranges. So Higg uses life cycle assessments (LCAs) and tries to come up with a measurement for the average impact associated with a kilogram of material, whether it’s wool or lyocell, organic cotton or cashmere. 

Higg looks at the cradle-to-gate impacts of material manufacturing across five different impact areas: greenhouse gases, water efficiency, eutrophication, fossil abiotic depletion, and chemistry. Simply put, it only considers how materials are made. It does not currently consider how long they last, how they are taken care of, whether they’re linked to plastic pollution, or what happens to them when consumers are done with them. For example, it does give a lower impact score to materials that have been recycled, but doesn’t consider how recyclable a material is — an important distinction. It also doesn’t consider the social impacts of a material like alpaca or silk, both of which are traditional industries that financially support low-income rural farmers. 

But Fibershed founder Rebecca Burgess says Higg is encouraging us to expand our use of fossil fuels, by pushing people to use plastic faux leather instead of real leather that is a byproduct of food production. “The problem is, it’s a measurement framework that doesn’t look at the consequences of itself,” she says. “It’s set us up for a continual reliance on fossil carbon.” She mentioned to me the Formosa Plastics plant in Texas, which was releasing millions of plastic bits into the Texas gulf coast waterways up until it was ordered to stop by a court last year. Because oil spills and plastic pollution aren’t measured by Higg, polyester made from those nurdles ends up looking better for the environment than natural materials.  Burgess admittedly may be a wee bit biased, since she runs a nonprofit dedicated to promoting local and natural textile production. But she is nothing if not fiercely grounded in science. “Their idea of cradle is not my idea of cradle. They’re starting at the nurdle plant. I want to start at the point where we extract the fossil fuels.”

And then there’s the garment itself. It doesn’t matter if the cotton is organic if the t-shirt is worn once and thrown away. “How many times a garment is used, it’s actually the most important factor,” says Roos, who points out that polyester can actually make a garment last longer. 

This isn’t due to a nefarious plan to make fast fashion companies look good, as I’ve seen it suggested. It’s just that there’s no agreed-upon way to measure these impacts yet. “The Higg MSI only leverages methodologies that are more broadly accepted as inputs,” it says on its FAQ page about microfibers. “Once a peer-reviewed, published, consensus methodology is available, SAC plans to incorporate it into the MSI ranking, and weigh microfiber impacts amongst the other critical issues.” It says the same of biodegradability of materials. Which, fair. 

OK, so we should be aware that Higg only applies to a certain set of sustainability factors. But even how it measures these is problematic. 

An Indian farmer holds a paddle with organic inputs.
An Indian cotton farmer in Gujarat shows off his organic, plant-based inputs.

There’s Not Enough Good Data for Natural Fibers

One of the biggest shortcomings of the Higg MSI is that it’s a global average. And this tends to favor standardized fibers made in a factory. “Polyester fiber spinning, if you collected data from one large spinning mill, then you could actually get rather representative data for polyester fiber in general,” Roos says. But not for cotton farms. Plus, it’s widely known in the consumer product and packaging world that corporations can and have commissioned LCAs that make their cheap, disposable products look better than reusables. That isn’t something smallholder farmers can do. 

“The models are only good as the data used to generate them,” said Paige Stanley, researcher and PhD candidate at UC Berkeley Department of Environmental Science, Policy, and Management, in a webinar hosted by the nonprofit Fibershed this past summer. “Greenhouse gas emissions can vary widely, due to differences in precipitation in different areas, or the types of production systems. Those global and national estimates don’t do a good job of picking up on those differences.” 

The SAC confirmed to me during their webinar introducing the new and improved MSI this summer that the cotton data represents a global average, except in the case of branded Cotton made in Africa (CmiA). “We are currently looking into options for adding more specific geographic locations in a future data update,” they said. 

We Shouldn’t Be Focusing on the Fiber Type, But How It’s Made

Fiber choice tends to get all the attention, especially from conscious consumers. But that can be misleading. “One of my main frustrations is that the entire climate impacts from fabric — and it has nothing really to do with the raw material, the fiber type — it’s mainly driven by the fuel use in all the processing,” Roos says. “Cotton fiber is not fossil-free. There’s a lot of truck driving, and the ginning operation, which is often or mostly driven by fossil fuel.”

“Regardless of the fiber you choose, you should choose the right supplier to see that your cotton doesn’t cause water scarcity, your polyester doesn’t cause local pollution,” Roos adds.

It Doesn’t Measure Regenerative Practices

Typical life cycle analyses don’t include data on regenerative practices either, the healing and carbon sequestration that certain methods of farming and ranching can achieve. (If this is your first time encountering this concept, we’ve written about regenerative fashion and you should check that out before going further on this deep dive.) This isn’t unique to Higg. 

Ecosystem services that regenerative farming and ranching provides, such as biodiversity, water filtration and more, aren’t included in LCAs. “[Higg data] tends to come out not in favor of systems that we know are improving ecosystems and the landscape,” Stanley said.  

cow looks out from a field
A cow in a Nicaraguan field in the high-altitude rainforest region. Cows are the only way to raise food in arid parts of Nicaragua, but might not be the best choice for rainforests, because they lead to cleared land. Higg does not account for this difference.

Let’s talk about cow leather for a moment, because it is a lightning rod in this debate and also a great example of all these concepts. 

“Before we started with fossil oil consumption and producing a lot of anthropogenic carbon, we had a lot of animals, Roos points out. “We had even more animals before the buffaloes and elephants were shot, and we were still in balance and harmony. Livestock that gives us meat, wool, leather, candles, glycerine — so many products — stands for 15% of climate emissions, in total. In my world, I think focusing on the other 85% is better. Methane, a major output from livestock, also only stands at 10% of greenhouse gas emissions. But somehow when we talk about methane, we always end up at, ‘eat less meat.’”

Plus, while methane is more powerful than carbon when it comes to warming the planet it “doesn’t last as long in the atmosphere, which isn’t captured,” Stanley pointed out. It’s bad now, but in ten years, it’s pretty much dissipated.

If we raise cows in a way that mimics the way, say, buffalo interact with grassland, we could potentially sequester around 1.3 metric tons per hectare. A cattle ranch and its leather would thus have a positive impact on the environment. But, that isn’t captured in the data that Higg uses. And if that isn’t captured, then brands won’t be incentivized to switch to regeneratively raised cow leather, which is a huge missed opportunity to mitigate climate change. 

Maybe cows shouldn’t be raised in Brazil at all, given that it’s dominated by rainforest and hard to track where leather comes from. But Higg’s data says Brazilian leather has a lower impact. “Fertilizer use in pasture in Brazil is very low (as cattle farming is based on grazing) leading to lower impacts in these impact categories compared to the US,” they said as explanation during the webinar. So in a weird twist, Higg is encouraging brands to switch to Brazilian leather, even as brands vow to stop sourcing leather from there because the Amazon was on fire. Go figure. 

And then there is the “eutrophication” measurement. This means the potential for polluting local waterways with too much nitrogen and causing toxic algae blooms. That can come from synthetic fertilizers for crops or an overabundance of manure. “The rapidly changing nature of raising livestock over the last century has also contributed to a sharp increase in nutrient levels,” The World Resources Institute says. But that’s not due to the cows themselves, but the way they’re currently raised: intensively, in feedlots that produce too much manure that is either stored in leaky lagoons or spread overenthusiastically on farms. If you have cows rotated quickly over a well-managed ranch, depositing cow pies where they do, that’s perfectly fine. 

“Eutrophication is just a consequence of having too much of a good thing in one place, like when you have too much manure running into a river system,” Burgess points out. “But nitrogen is essential for growing plants. Eutrophication to me is just a mismanagement problem.” 

A herd of alpaca wanders a lush mountain valley two hours outside of Cusco, Peru.

For all these reasons, the alpaca data also does a terrible job of capturing alpaca fiber’s actual impact of the environment. The study cited in Higg’s metadata is based on alpacas in a Swiss zoo that were fed alfalfa, but according to FAO data listed within Higg’s MSI tool, 85% of the alpacas in Peru are raised by smallholder farmers. And Alpacas are native to Peru’s ecosystem. According to Higg’s FAQ, alpaca fiber scores so high because of high eutrophication, again, related to their manure. If there were too many of them at a factory farm that dumps into a river, that would be a problem. But there’s been no evidence of that. Instead, they wander their ancestral home of grassy mountain hillsides. 

Weirdly enough, however, Higg gives kangaroo hide a low impact score. “Kangaroos are commercially harvested from the wild, therefore no impacts are assigned from the on-farm/animal husbandry phase. Only processing and transportation impacts are included,” it says in its FAQ. Higg makes it look like there is a vast gulf of difference between kangaroos’ and alpacas’ impact on their native habitat. In reality, there’s probably not. 

You’re Not Actually Supposed to Compare Materials to Each Other

When I attended the webinar put on by the SAC and Higg this summer, I asked them some rather blunt questions about this. “I’ve received several communications from PETA and other activists who are using the Higg store to advocate for not using animal fibers, including silk, alpaca, and leather,” I asked in the Q&A. “Do you think that interpretation is correct?

“In many cases, comparing between material categories doesn’t make sense,” a rep answered. “If customers are looking for cotton t-shirts, I can’t just switch to polyester since the functionality of the material is different. I should focus on what I can do to lower the impacts of my cotton t-shirt (such as by using recycled content). There are going to be instances where comparing across categories does make sense, when materials perform similar functions, but understanding any differences in performance and functionality is always important to consider.” 

“Switching from one fiber to another solves one problem, but it might create a new one,” Roos affirms. “It doesn’t make sense just comparing straight climate impact or water scarcity when the fibers are both used in different products and create different problems.”

Instead, Higg encourages brands to choose the material that works the best for their products, then find the best version of that material. And Higg does allow you to do that. You can choose the base material, then tinker with its chemistry certification, how it’s dyed, knit, transported, and more to find a more accurate assessment of its impact. 

I’m sure the experts at large brands are using Higg the way it was intended. But it seems that the SACs message has a tendency to get lost (or in the case of animal rights activists, deliberately hidden).  

“Small designers will go in to select their materials, and not consider performance,” says Marzia Lanfranchi, a sustainable cotton consultant who used to work at Burberry and FatFace. “The Higg Index is a good tool, but you still have to use your brain.” 

Higg Makes Changes

In November, Higg announced it would be retiring the single, aggregated material score, after coming under heavy criticism from industry groups representing silk, leather, and alpaca. While the individual scores for eutrophication, chemical usage, water scarcity, greenhouse gases and fossil resource depletion will still on balance favor synthetic materials, the lack of one score should make it more difficult for PETA and small brands to misuse the data. (Though I’m sure PETA will try.)

Plus, next spring, Higg will launch the next version of its product module, which will include the use phase, and end-of-life considerations. 

But it’s not just Higg that needs to improve its processes. When responding to allegations that its data is skewed, it always invites the submission of new and better data so it can update its assessments. So far, associations representing industries like alpaca and silk have been slow to conduct LCAs on their textiles, but these misconceptions about natural fibers might be the push they need to do it. And having more and better data will be a win for the fashion industry. 

What Should Consumers Do With the Data? 

Higg has been testing out product modules on some e-commerce sites that tell consumers about the sustainability of the items they’re looking at. Sometime in the next year or so, Higg will be making all its data public for anyone, including consumers, to use. So when that happens, how should you use it to make better choices? 

My advice would be to do the same as designers and brands. Look for the item that you need and want, something that is high quality from a trustworthy brand that does take-back and repairs. If you find two similar items, all else being equal, then you can use the sustainable rating of the product to make your final decision. 

Hopefully, by then, the Higg Index will have better data and you can be confident you made the right decision. 

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