A global plastic treaty will only work if it caps production, modeling shows

An international agreement to end plastic pollution is due to be sealed this year in Busan, South Korea. At the penultimate round of negotiations, held in Ottawa, Canada, Rwanda and Peru proposed a target to cut the weight of primary plastics produced worldwide by 40% by 2040, compared with 2025.

This is the first time that a limit on the production of plastic has been considered at the UN talks aiming to develop an international legally binding instrument to end plastic pollution. Of the potential mechanisms for tackling plastic pollution, a cap on plastic production was the most hotly debated, but one has not made it into the draft text of the treaty—not yet, at least.

However, all efforts to scientifically model the extent of plastic pollution in the future assume that restricting how much plastic the world makes each year will be necessary (among other measures) to curb its harmful presence in the environment.

In a 2020 study I co-authored, my colleagues and I found that primary plastic production—the creation of new synthetic polymers, largely from fossil fuel—will need to be 47% lower in 2040 compared with the rate measured in 2016. This scenario would involve plastic production falling by as much as our research team considered practicable.

Cutting production almost in half and using all other strategies, such as ramping up recycling and disposing of plastic waste in landfills or via incineration plants, would still leave residual pollution in 2040. In fact, just under 50 million metric tons of plastic would still be flowing into the ocean and rivers each year or accumulating on land where it may be burned in the open and create even more pollution.

In a 2022 report, the OECD estimated that cutting demand for plastic by 33% relative to 2019 (and enhancing recycling alongside preventing plastic escaping the waste management process) would almost eliminate mismanaged plastic waste by 2060—that is, plastic that end up as pollution in the environment.

A combination of measures such as these is considered the most effective scenario in cutting pollution. Again though, the OECD model projects slightly over 50 million metric tons of plastic waste being mismanaged annually in 2040. For the accumulation and burning of plastic in the environment to stop, we would have to wait another two decades.

The 40% reduction target floated in Ottawa is generally consistent with what these models suggest is necessary to substantially reduce plastic pollution in coming decades. Whether such a production cap is plausible however is still poorly understood. With plastic production still increasing, it is unclear what policies would reduce it so steeply in just 15 years—and what their side effects might be.

Reducing plastic production would require marked shifts in our lives for which there is little precedent. It could involve massive changes in how we behave as consumers, how products are designed and delivered to us—and so on.

A 40% production cut would probably entail slashing the amount of packaging and single-use plastic made worldwide. These shortlived products account for around half of all plastic production and become waste quickly. Essentially, this would reverse the trend in material use since the mid-20th century.

Every year without production caps makes the necessary cut to plastic production in future steeper—and our need to use other measures to address the problem greater.