In the last days of August, an influx of slender women to midtown Manhattan signals the onset of fashion week, the biannual round of catwalk shows. After passing on to London, Milan and then Paris, the prevailing sensibility coheres into an agreed style.

Only this season, the last of the decade, that sensibility may be about to evaporate. A summer of fire in the high Arctic and the Amazon was capped by something to celebrate; the arrival in New York harbour of the 16-year-old Swedish climate activist Greta Thunberg after she crossed the Atlantic on an emissions-free yacht.

Her first duty, she said, was to join a climate protest ahead of the UN climate action summit in September. “We need to stand together and take action because otherwise it might be too late.” She added: “It is insane that a 16-year-old would have to cross the Atlantic to take a stand … The climate and ecological crisis is a global crisis and the biggest humanity has ever faced.”

If anyone is in the mood to buy personal luxury goods, it would be surprising. Fashion, which has avoided environmental scrutiny, is faced with increasing consumer and regulatory pressure to improve its profile in a globalised market that is now said to generate €1.5 trillion annually.

Selling the dream of fashion and luxury while reassuring customers that it can be done without further damaging the planet is a tightrope walk. Over the past month, that tension between consumption and the climate crisis has reached the international stage.

Under the guidance of French president Emmanuel Macron at the recent G7 summit in Biarritz, 32 fashion companies signed a “fashion pact” to emphasise sustainability in the industry. They included some of the largest luxury brands in the market – Chanel, Ralph Lauren and Prada – as well as “fast fashion” producers, including H&M Group and Zara. Fast fashion retailers have come under fire from environmental campaigners for encouraging a market that sees around 300,000 tonnes of clothes dumped in UK landfills each year,

Greta Thunberg, Swedish climate activist, travelled to New York after lobbying the the French National Assembly. Photograph: Lionel Bonaventure/AFP/Getty Images

“We are taking our responsibility through collective action and common objectives,” said François-Henri Pinault, chairman and chief executive of Kering, the French luxury-goods conglomerate that owns Balenciaga, Gucci, Alexander McQueen and Saint Laurent, among others. The so-called pact, though, is notably short of firm goals to reduce planet-heating emissions.

According to a United Nations study, the fashion industry is responsible for about 10% of all greenhouse gas emissions, 20% of all waste water, and consumes more energy than the airline and shipping industries combined.

The figures are disputed but the message is clear: fashion is a major polluter, and in an industry that depends on human desire for the new, questions hang over it like a dead weight.

Few believe that the French fashion houses would act if it were not for growing consumer pressure. Kering has been publishing an “environmental profit and loss” statement for its products since 2015; rival LVMH, the owner of Louis Vuitton, Christian Dior, as well as a stake in Stella McCartney – the label famous for banishing fur and leather – has yet to follow suit.

But others have joined the rush to publish updated public sustainability reports. “The fashion industry was behind the curve on this, and it’s playing catch-up to the way people feel,” said Tim Blanks, a leading analyst at Business of Fashion. “Fashion brands are being held to account and developing an awareness and sense of consequence that it has been truly oblivious to.”

The supermodel Amber Valletta says as much as she appreciated being told she looked good in this or that outfit, she often felt a disconnect between her job and the business. Around 15 years ago, she told the Observer, she “started to connect the dots with the environment and cheap labour”.

Fashion, she claims, is an insular world with maybe a thousand people at the top of the industry: “Fashion is an insular world. There aren’t that many people who hold the power. We live in a fashion bubble, but it trickles down in ways we’re not really conscious of, to fast fashion and cheap labor. The reality is were affecting a lot of people and the planet.”

Fashion is responsible for 10% of greenhouse gas emissions and consumes more energy than airline and shipping combined United Nations report

Valletta recently shelved a fashion line on the basis that it would just be adding to the amount of stuff available without coming up with an environmentally innovative way of doing it. “Something went wrong. We lost meaning in what we were doing, and people lost meaning between what they need and what they buy,” she said. “The question is, how are we going to do things the right way? It’s like we have to change the way we make things, sell things and wear things. Everything really.”

She’s currently planning a documentary looking at the underlying issues. “It’s important that people at the top of the industry become the leaders of the change. In the past we fought for all sorts of causes. Now we have to fight for sustainability. Now we have to fight for the planet,” she said.

To be truly sustainable, brands may have to consider producing less at a time when consumers want more. According to a report by the Global Fashion Agenda, any progress toward sustainability is actually decreasing – by as much as a third. Brands, it warned, have yet to solve the trade-off between growth and managing their environmental footprint.

To be sustainable, brands have to consider producing less when consumers want more. Photograph: Mohammed Anwarul Kabir Choudhury/Alamy Stock

With clothing production expected to hit 102 million tonnes a year by 2030, sustainability efforts need to accelerate to avoid even more strain being placed on the world’s resources.

Blanks, who helped chair this year’s fashion sustainability summit in Copenhagen, said the issues are inclusivity and accountability: “If you are accountable, then you have a sense of cause and effect and it permeates everything you do. If you are inclusive, then you have to have respect for the environment.”

“You shouldn’t underestimate the work that’s being done at different companies,” says Pinault, who is trying to get companies to sign up to eliminating single-use plastics and accelerate the industry’s transition to renewable energy. “The problem is that we’re all working in our little corners, so despite our efforts, everything we do is completely offset by the growth,” he added.

Kering itself, which has gone further than many to manage this equation, has seen its environmental scorecard (measured by air emissions, water pollution and land use) getting worse.

The emerging argument, it seems, is to buy less but buy better on the principle that consumers will treasure and reuse those clothes and get off the seasonal treadmill. “Couture is more sustainable in the sense that you’re paying a lot of money for something that’s produced to an incredibly high standard and there’s no disposability written into it,” Blanks said.

The recent Valentino haute couture show, he added, was so spectacular that it received a 10-minute standing ovation from an audience where some were moved to tears of joy:

“It’s the ethos of the heirloom – the highest end of the market is where you see this ethos realised in a very real way.”

The Valentino show that was part of Paris Fashion Week in July. Photograph: Peter White/Getty Images

Of course, haute couture is beyond the budget of most consumers, but the underlying principle – replace seasonal binge-shopping with clothes that express thoughtfulness and care – is the same. “It’s much more fun because its about creativity and self-expression, and that’s more challenging and rewarding,” Blanks said.

This isn’t new to environmentally conscious millennials – many have adopted Earth-saving circular economy resellers like DePop, Farfetch’s Second Life and the RealReal en masse. In a season when the New York fashion emporium Barneys went bankrupt, the RealReal is valued at $2.39bn.

“Our focus on extending the life cycle of luxury and keeping pieces in circulation through resale offers a more sustainable way to shop luxury,” said RealReal’s Michael Groffenberger.

The company acts as a middleman for secondhand haute couture between buyers and sellers – so-called “authenticated luxury consignment”. Groffenberger notes that 64% of its millennial sellers (or consignors) say that environmental impact is the key reason for using the service.

There are signs too, that the design community is beginning to wake up. Italy’s Prada has said it wants to source all of its emblematic Nylon accessories from recycled materials, including ocean waste by the end of 2021. Giorgio Armani and Versace have both stopped the use of certain materials.

“We have years of talk but now change is at the forefront,” said Orsola de Castro of Fashion Revolution, a group campaigning for greater industry transparency. De Castro credits the growing awareness to several events, including the Rana Plaza disaster in Bangladesh in 2013, growing awareness of the environmental damage from microfibres, and the impact of British fashion house Burberry destroying £30m of stock to guard against conterfeits (the French government floated a plan earlier this year to outlaw the widespread practice of destroying unsold clothes and luxury goods).

“The negative impact of the fashion industry has reached its nadir and now consumers are beginning to ask the right questions,” said De Castro.

Recently the UK protest group Extinction Rebellion announced plans to shut down London fashion week

A reaction against the excessive consumerism of fashion is taking shape: recently the UK protest group Extinction Rebellion announced plans to shut down London fashion week, which starts on 13 September. “In recognition of the existential threat that faces us, we ask the British Fashion Council to be the leaders the world needs now and to cancel London fashion week,” the group wrote in a letter to the British Fashion Council. There is little hope of that happening, but in New York nine labels have so far refused to stage fashion shows at Hudson Yards, a vast development on the city’s westside in protest against real estate developer Stephen Ross, who recently held a re-election fundraiser at his Hamptons home for climate-change denier Donald Trump .

Fashion is worth £32bn to the UK economy and Britons buy more garments than any other country in Europe. They also, it would seem, throw a lot away.

In protest at the 11 million items of clothing that end up in UK landfills each week, the model Stella Tennant and charity Oxfam recently launched their campaign against more than 50 million single-use items of clothing purchased by Britons this summer.

For their Second Hand September campaign, the pair are asking consumers to abstain from buying new clothes for 30 days, and shop, ideally, at Oxfam to raise money for its programmes.

As the Financial Times pointed out, the campaign comes “slap at the beginning of the show season”.

Tennant points out that she’s never been a seasonal shopper: “The things I loved 20 years ago I still love. The enemy is our insatiable desire for the new. We’re human, and of course we love new things, and it’s so exciting to see what these brilliant, creative designers have come up with.

“In terms of sustainability, we’ve become very indulgent in how much stuff we buy and then how much stuff we discard.”

But that, she points out, is not a Valentino couture dress: “The skill and craftsmanship involved, and so many people making something so extraordinary … it’s difficult to get the balance right, and I’m not suggesting that should stop, but we need to be more thoughtful as consumers.”

That sentiment is echoed by designers. New York-based designer Maria Cornejo, who has won several awards for sustainability, is currently involved in a collaboration with carmaker Hyundai to “upcycle” excess leather from car seats in her designs.

“Nobody is going to stop consuming, but it makes economic and environmental sense to reimagine materials that have had a prior life,” she said. Unless you’re buying a second-hand car, people only buy things because they desire them, not because it’s politically correct, Cornejo reasons.

Activists from Extinction Rebellion wearing coats made of living grass protested outside London Fashion Week in February 2019. Photograph: NurPhoto/NurPhoto via Getty Images

If some companies are jumping on the bandwagon and “greenwashing” their products, that’s better than taking no action at all, said Cornejo. “It’s what has to happen because at least they’re going in the right direction. It’s the future. Everybody has to take some responsibility for what’s going on.”

That message even seems to be filtering through to the red carpet of showbusiness, where the habit of only wearing clothes once for photographs first started before it filtered down to Instagram, fast-fashion and the mass-market.

Fashion glossy US Vogue published a story titled Earth to A-Listers calling on movie stars to bring the sustainability issue to the red carpet during award season following the UN’s “terrifying” climate report.

“Wouldn’t it be powerful to see these same celebrities re-wearing gowns they’ve worn in the past –advocating against the throwaway culture that sees consumers toss away garments after a single use, like they do iced-coffee cups?” asked writer Nicole Phelps.

Model Michelle Hicks had her own take on red-carpet tyranny: “It became a rat race to wear the newest, coolest thing. You get photographed in it once and that’s it. And that’s bad.”

This week Hicks is going to fashion editor and stylist Carine Roitfeld’s Harper’s Bazaar party in her own 20-year-old Galliano dress. “It’s stunning, so why not wear it again? Why not recycle?”