Editor’s Note: Watch the video below to see highlights from Becky Anderson’s interview with Stella McCartney, which aired on “Connect the World with Becky Anderson” on Thursday.

CNN  — 

Stella McCartney has called on world leaders to introduce new tariffs on leather goods, as well as fashion items made from polluting or environmentally unsustainable materials.

Speaking to CNN’s Becky Anderson at the UN’s Climate Change Conference (COP28) in the United Arab Emirates this week, the fashion designer said she can be taxed at a rate that’s “up to 30% more” for non-leather bags or shoes entering the US market.

“If I put a sliver of animal leather onto that same product, the tax disappears. That is a law that needs to swap,” said McCartney, calling current tariff structures “crazy.”

“You need to be penalized if you’re cutting down the rainforests and using cancerous toxins to tan leather and human welfare is at risk.”

King Charles III (left) speaks with, Prime Minister Rishi Sunak, Stella McCartney and US Special Presidential Envoy for Climate John Kerry (right), during a reception at Buckingham Palace ahead of last year's UN climate change summit.

A longstanding advocate of sustainable and vegan fashion, McCartney said she felt alone in her drive to develop new alternative materials. “The reality is I’m still the only one working this way,” she said.

The designer also used COP28 to announce a new collaboration with Mango Materials, a company using waste methane gas to feed bacteria that produce a biopolymer for use in items like sunglasses frames.

“These bad ugly businesses are getting the tax breaks; they’re getting the incentives,” McCartney said, addressing Mango Materials CEO Molly Morse — who appeared alongside her during the CNN interview — after the civil engineer said her startup would consider using excess methane from oil and gas companies to produce its biomaterial.

Your business should be getting paid all of that benefit to be making them clean,” McCartney continued.

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Watch: Stella McCartney in conversation with CNN's Becky Anderson at COP28.
04:52 - Source: CNN

In a wide-ranging interview, the designer called on COP28 delegates to “stop ignoring that the fashion industry is one of the most harmful industries to the world.”

The fashion industry’s environmental impact is difficult to quantify, but the United Nations Environment Program said fast fashion contributes “around 10% of global greenhouse gas emissions due to its long supply chains and energy intensive production.” Animal rights group PETA, which is now targeting the wool, leather and down trades, meanwhile claims that more than 1.4 billion animals, including cows, sheep and goats, are killed each year for leather.

“We need policy change. We need laws to be looked at. We need limitations, then we can all work together as an industry,” said McCartney.

Faux leather faux pas

While some animal rights advocates push for leather substitutes, many come with their own environmental costs.

Materials marketed as vegan leather are often made from two plastic polymers — polyvinyl chloride (PVC) and polyurethane (PU), or a combination of the latter and some kind of natural material. While synthetic leather is animal-free and has a lower environmental impact than animal leather, according to a study in the journal Nature Sustainability, its manufacture often uses hazardous chemicals and fossil fuels. And like most plastics, the materials can take centuries to break down.

There are new alternatives being produced, including biodegradable “leathers” made from fungi or bacterial cellulose from industrial fruit waste, but not all are widely available on the market.

A model walks the runway for Stella McCartney at Paris Fashion Week.

As part of a move away from fossil fuel-based synthetics, McCartney’s label has used Mylo, a material made from mycelium (the root-like structures of mushrooms), to produce a line of handbags called The Frayme Mylo. Earlier this year, however, the firm behind Mylo, Bolt Threads, announced that it had ceased operations, telling Vogue Business that the company had been unable to sufficiently scale up production.

“I’ve been a fashion designer for my whole life, and I’m not as interested in what the next silhouette is, or what the next color is in 2024 and ‘25,” McCartney told CNN. “I’m like, ‘What’s the next material? What’s the next solution that we can give to the world to make it, a better planet?’”

McCartney, whose label has committed to achieving net-zero carbon emissions by 2040, said she is focused on producing materials from widely available by-products that are not grown for the fashion industry.

At COP28, her delegation showcased more than 15 projects pioneering biomaterials and plant-based alternatives to plastic, leather, fur and traditional fibers. Among them was an alternative leather made from grapes, developed with Champagne brand Veuve Clicquot, and garments produced from a biologically recycled polyester that can be recycled again and again.

She also announced that she will be working with PETA to promote alternative materials for leather, furs and feathers.