Mismanaged plastic waste: the baseline behind every plastic credit

What mismanaged plastic waste means

Plastic waste is mismanaged when a formal system does not keep it out of the environment. In the most widely cited global assessment, researchers led by Jenna Jambeck treated waste as mismanaged when it was littered or disposed of in ways that let it escape, such as open dumping and unsanitary landfill. Mismanaged waste is the pool from which most ocean plastic and river and coastal leakage comes. It is also the raw material that plastic credit projects aim to divert.

What the 2015 global estimate found

Jambeck and colleagues, publishing in Science in 2015, estimated that 275 million tonnes of plastic waste were generated in 192 coastal countries in 2010. Between 4.8 and 12.7 million tonnes of that entered the ocean from land in the same year. The range is wide because collection and disposal data were patchy in many countries, and the authors relied on modelled assumptions to fill the gaps. The study remains the most cited baseline, but it describes 2010, and waste systems have changed since then.

Why the baseline decides whether a credit is real

A plastic credit claims that a tonne of plastic was collected, recycled, or otherwise kept out of the environment because of a project, and that this would not have happened without the credit being sold. Both parts depend on the baseline. The project has to show that the plastic was at risk of leaking without intervention, and that its collection exceeds what would have happened anyway. Where a region already collects most of its waste, the credit's contribution is hard to demonstrate. Where collection is weak and waste is dumped near waterways, the case is stronger, but it still needs to be measured.

How projects estimate their baseline

Most methodologies cannot observe the counterfactual directly. Instead they build a catchment model. The project area's population, waste generation per person, collection coverage, and disposal practices are estimated, usually from national or municipal waste studies, and the share likely to leak is then calculated. Each input carries uncertainty. A small change in assumed collection coverage can move the estimated leakage considerably, which is why the source and year of each input matter as much as the final figure. Two projects in the same country can therefore report very different baselines simply because they use different datasets, so a buyer should compare the inputs, not only the headline tonnage.

Questions to ask a project developer

Before buying, a buyer can ask a few specific questions that show whether the baseline is credible. Which dataset defines the baseline, and what year does it come from? Can you show the catchment boundary on a map? What share of waste is currently collected, and what evidence supports that figure? Has the baseline been revalidated since the project started? Does the project count plastic that informal collectors already recover and sell? If that material would have been recycled anyway, it does not represent additional diversion.

Mismanaged waste and the wider policy picture

Mismanaged waste is also why policymakers focus on collection systems. Extended producer responsibility schemes, discussed elsewhere on this site, fund collection in many of the same places that plastic credits target. Credits and EPR can therefore compete for the same tonnes. Buyers should check that the plastic a project credits is not already counted by a public or producer-funded scheme, because a tonne cannot usefully be claimed twice.

What this means for buyers

A plastic credit is only as strong as the baseline behind it. Buyers do not need to become waste statisticians, but they should be able to say where the baseline comes from, how old it is, and whether an independent body has verified it. A project that cannot answer those questions should be treated as unproven, however attractive its price or story. The 2015 global estimate is a useful starting point for understanding the scale of the problem, but it is not a substitute for project-level evidence.

Frequently asked questions

Is mismanaged waste the same as litter?

No. Litter is one form of mismanagement, but the term also covers waste that is dumped in open sites or disposed of in ways that let it escape into the environment. In the 2015 global assessment, both fall into the pool of waste that is not securely managed.

Is the 2015 estimate still the right number to quote?

It is the most cited global estimate, but it describes waste generated in 2010 and relies on modelled assumptions where data were missing. It is useful for explaining the scale of the problem. It should not be used as the baseline for an individual project, which needs local and more recent data.

Why do two projects in the same country report different baselines?

They usually draw on different datasets, catchment boundaries and assumptions about collection coverage. This is why a buyer should compare the inputs behind each baseline and not only the headline tonnage.

Where can a buyer find a project's baseline?

In the project design document and the monitoring reports published on the registry record. If the baseline inputs are not published or cannot be explained by the developer, treat that as a gap to resolve before buying.