The recycling bin has always sold a simple story: toss something in, and it goes ‘away’ to be responsibly handled. The illusion cracked in 2018, when China, after 30 years of quietly importing much of the world’s poorly sorted recyclables, refused to absorb any more foreign waste. This single policy shift severed a market that many Western nations had become dependent on and forced these countries to confront their own recycling streams by investing in domestic infrastructure, finding new import partners, sending more to landfill or cutting local recycling programmes1,2 — and revealed to the public that ‘away’ was really just someone else’s backyard.

The plastics trade is just one thread of a larger pattern in which countries, primarily in the global south, bear the brunt of wealthier nations’ consumption. Today’s rapid pace of technology and product turnover, from electronics to fast fashion, ensures that waste builds up more quickly than can be responsibly managed. According to the United Nations’ 2024 Global E-waste Monitor3, the world is generating electronic waste five times faster than it is being recycled.

The problem of waste exposes an uncomfortable tension in the materials community: our field’s drive to innovate and make comes with a responsibility for what happens to these creations when we are done with them.

‘Circularity’ has become a popular banner for action in materials science. A circular materials economy aims to keep materials in use for as long as possible through reuse, repair and recycling. Materials researchers contribute to circularity both upstream (preventing waste in the first place with new chemistries, designs and manufacturing methods) and downstream (turning waste into value with new sorting and recycling technologies).

In this Editorial, however, we underscore two caveats of materials circularity. First, circularity is not necessarily synonymous with sustainability4. Whereas circularity focuses on recovering resources, it tends to overlook other aspects of sustainability, such as energy use and emissions over the whole life cycle, and effects on social equity, human rights and biodiversity. Second, materials research is only one part of a much larger system. Lab breakthroughs alone cannot deliver circularity. Without appropriate regulation, behaviour, infrastructure and economic markets, even brilliant materials research will fail to make its intended impact.

Consider batteries: research efforts make them last longer, store more energy, or easier to repair or recycle. Yet electronic devices today are often designed — whether for thinness, waterproofing or planned obsolescence — to prevent battery removal or repair of other failed components, forcing the consumer to discard the entire device and buy another. Right to repair laws and the European Union’s new battery replaceability design rules for manufacturers help but will make little difference if consumers find buying the newest model cheaper, easier or just more exciting. Similarly, new battery recycling technologies will hit dead ends without consumer education, e-waste collection infrastructure, market demand for recycled battery materials or financial incentive to reuse resources over mining new minerals more cheaply.

Given these caveats, what can the materials community do to contribute meaningfully to a circular materials economy? It should begin by resisting greenwashing and face-value acceptance of ‘green’ buzzwords, not only from marketers, but also in research — doing the hard carbon math and life-cycle analysis to determine whether a proposed solution does what we expect. Biodegradable plastics in a landfill can emit carbon that might be better sequestered, and they contaminate recycling streams if mistakenly put in the recycling bin. Products that mix in downcycled materials or bio-feedstocks, such as t-shirts woven from recycled plastic fibres and plastic bottles made 30% from plants, are only more complex and less recyclable at their end of life. These materials might still be the most sustainable option in certain scenarios, but researchers should aim to support such claims with evidence.

Materials researchers should also seek to connect with the broader value chain. Well-intentioned decisions can create surprising consequences that make sense only through the lens of other academic disciplines. Plastic bag bans spawned a crisis of reuseable tote bags that might ultimately cost more energy to produce, are less straightforward to recycle and have been linked to forced labour. Paradoxically, circular initiatives can even increase production and consumption through the economic and behavioural mechanisms of the rebound effect5, negating gains in sustainability.

Materials circularity research must be grounded in social, economic and regulatory realities. This means stepping beyond our comfort zones to hear views across the entire system, not just from those who share our technical perspective.

To catalyse this conversation, we are launching a new Series that asks tough questions about materials circularity from those within and outside of our community. On the plastics crisis, we publish a reflection on historical waste management, a call to quantify the plastics lost to ecosystems and a guide for plastics manufacturers to assess their use of additives6. We hear from an architect aiming to reform the construction industry through materials passports and explore battery regeneration, wind turbine blade recycling7 and a bold way to reuse the atoms in municipal sewage sludge. In upcoming articles, we talk to an industrial ecologist with decades of insight into the relationship between extended producer responsibility laws and materials design, and we untangle how waste management works on a practical level in global megacities.

The ongoing Series will bring together voices from academia, industry and policy to examine what circularity really means across energy, electronics, fashion, plastics, construction and more. We hope that the different angles challenge assumptions, inspire new approaches, and encourage an atmosphere of honesty about whether our actions deliver real change, or simply good intentions.