Scientists rallied last week to support delegates working on a global treaty to eliminate plastic pollution at the United Nations Environment Programme (UNEP) headquarters in Nairobi.

But researchers told Nature that progress was disappointing. “We now only have about a year left in this process and are nowhere near where we need to be,” says Douglas McCauley, an ecologist at the University of California, Santa Barbara, who has modelled plastic pollution.

Plastic pollution: Three problems that a global treaty could solve

“These negotiations have so far failed to deliver on their promise,” said Ana Rocha, plastics-policy director for the Global Alliance for Incinerator Alternatives (GAIA), in a GAIA press release after 13–19 November meeting. The statement added: “A small group of mostly oil and plastic-producing countries halted progress toward an internationally binding legal document.”

“You get one shot at getting words on paper,” says McCauley. The treaty “should be specific, it should be binding, it should be ambitious”, he adds. He is hoping that scientists can steer delegates towards a strong agreement with firm promises. “Time is of the essence.”

Tallying the impacts

The process was kick-started in March 2022, when 175 nations voted to create a legally binding international agreement aimed at plastic pollution — a problem that has reached epic proportions since the 1950s. Humanity now manufactures more than 450 million tonnes of plastic per year, and about 22% of plastic waste is ‘mismanaged’: dumped or burnt in open areas rather than being placed in sealed landfill, incinerated or recycled. According to one estimate, the world is on track to accumulate roughly 12 billion tonnes of plastic waste in landfill and the natural environment by 2050¹.

Researchers continue to tally the impacts of this litter: plastic has formed islands in the ocean, been incorporated into reefs on the sea floor and even chemically bonded to rocks in river beds. They are also documenting a large number of environmental and health effects from plastic chemicals and microparticles in the air, at sea and on land². Tiny pieces of plastic have found their way into food, blood and breast milk, with as-yet unclear impacts.

A ‘zero draft’ of the plastics treaty was hammered out in September, after the second meeting of UNEP’s International Negotiating Committee (INC). It lays out more than a dozen issues to be tackled, including the reduction of plastics production, managing waste and the use of recycled materials, phasing out single-use plastics, promoting alternative materials and limiting the use of chemicals of concern in new plastics. The draft lists a few proposals for addressing each issue, ranging from setting hard targets to making softer declarations of intent.

Last week’s meeting, which marked the third session of the INC and the halfway point towards the goal of finalizing the treaty in 2024, saw the zero draft get longer, rather than narrowing down the options. The next session will be in Ottawa in April.

The meeting included representatives from governments, industry, advocacy groups and academia. The Scientists’ Coalition for an Effective Plastics Treaty, a group of some 250 experts from about 50 nations, is pushing for an agreement that will set legally binding targets to reduce plastics production, both for each signing party and for the planet as a whole. “We’re pushing really hard for prevention or reduction, all those things that are higher up the zero-waste hierarchy than just increasing recycling,” says Trisia Farrelly, an environmental anthropologist at Massey University in Palmerston North, New Zealand, and a member of the scientists’ coalition.

Striking images show plastic litter in the world’s most remote coral reefs

A separate High Ambition Coalition to End Plastic Pollution, including dozens of countries and chaired by Rwanda and Norway, is similarly calling for binding targets. Other nations, including Saudi Arabia, are pushing instead for countries to determine their own contributions to pollution-reduction goals, and are advocating an emphasis on boosting waste-management processes such as recycling, rather than restricting plastics production.

The scientists’ coalition is campaigning for chemicals of concern to be listed in an annex to the treaty, which can be updated in future. The latest research³ suggests that there are some 13,000 chemicals involved in plastics. More than 4,000 are known to be hazardous, says steering-committee member Bethanie Carney Almroth, an ecotoxicologist at the University of Gothenburg in Sweden, and 10,000 lack sufficient data. Only 1% are regulated through existing international environmental agreements, such as the Montreal Protocol to protect the ozone layer.

Scientists engage

Whatever wording the treaty settles on, researchers will need to work hard over the coming months to provide the data that policymakers need to set realistic targets, Farrelly says. “People keep on asking us,” she adds, “what percentage reduction should we be asking for, based on what evidence? And actually, we don’t have that yet.” The environmental-activism organization Greenpeace, based in Amsterdam, is calling for plastic production to be reduced by at least 75% from 2019 levels by 2040.

Three ways to solve the plastics pollution crisis

Ahead of the meeting, McCauley and his colleagues released an online tool that allows policymakers to plug in various targets and see the effects on waste. For example, a policy might set a specific cap on plastic production, phase out single-use plastics or regulate the amount of recycled material that must be included in new products. The goal, McCauley says, is to determine potential paths to zero mismanaged waste — or close to zero. “I can eliminate 90% of the problem using a very-high-ambition-but-not-impossible package” of policies, he says. “To me, that’s really optimistic.”

The model, which uses machine learning and incorporates economic and population trends, shows that “we have to be ambitious”, McCauley says. “A low-ambition treaty would be worse than no treaty at all,” he adds, “because then we are pretending we are solving the problem.”

An 11 November letter from a group of scientists calls for a more formal process for integrating science into the treaty. It also asks for the creation of a scientific body, similar to the Intergovernmental Panel on Climate Change, that would provide negotiators and policymakers with regular updates on the scientific evidence surrounding plastic pollution. This body would, for example, assess new research to help update targets and the list of chemicals of concern. “We have clearly called for delegates to establish a credible and transparent science engagement process for the INC,” says Margaret Spring, chief conservation and science officer at the Monterey Bay Aquarium in California, who is lead author of the letter.

“A vital part of making this treaty matter will be how much the scientific community engages,” says McCauley.