What is the output of the model? Only plastic flows or other environmental impact categories as well?
The model is designed to quantify key plastic flows and stocks in the global plastic system. It estimates the quantity of ocean plastic pollution expected under six scenarios between 2016 and 2040. It assesses the economic, environmental, and social impacts of the principal known solutions and technologies. The capital expenditure (CAPEX), operating expenditure (OPEX), direct employment, and GHG emissions associated with each future scenario are estimated.
Does the model consider the plastic waste that is disposed of in an uncontrolled way to the ecosystems?
Yes, the model considers plastic waste disposed of in unsanitary landfills, open dumps, littered on earth, in waterways, and through open burning.
Why are 36% of plastics out of scope, including textiles and building and construction etc.?
The analysis focused on quantifying leakage rates and solutions for municipal solid waste. Excluded plastics (e.g., hazardous waste, waste from furnishings, transportation, construction, and other industrial waste) are not typically entering municipal solid waste.
Are direct plastic pollution sources to the oceans through fishing and tourism included?
Robust estimates of maritime sources of plastic (anything leaking into the ocean from seagoing vessels, including fishing gear and shipping litter) are lacking, with estimates ranging from 10 to 30 per cent of total macro-plastic leakage. These have not been included in the quantitative analysis, but solutions to address these sources of plastic pollution are addressed qualitatively in the Breaking the Plastic Wave report.
The rate of mismanaged plastic waste is very important, how do we model that robustly?
Four main routes, through which land-based macro plastic waste enters the ocean, were modelled: 1) uncollected waste directly dumped into the water; 2) uncollected waste dumped on land that makes its way to the water; 3) collected waste deposited in dumpsites that moves via land and air into the water; and 4) collected waste dumped directly into the water by collection trucks. Estimated transfer rates of mismanaged waste to waterways were a function for example of the type of plastic (e.g., rigid, flexible, multi-material) and distance to waterways.
In a scenario where chemical recycling technologies (or to some extent solvent-based recycling) are included, how do you choose the feedstock that will be processed through these technologies?
Chemical conversion has a role to play in stemming plastic leakage to the ocean because it could create an economic sink for certain low-value plastic types that make up a high proportion of plastic pollution and which cannot be readily reduced, substituted, or mechanically recycled. However, for chemical conversion to help reduce plastic entering the environment, it needs to be profitable enough to cover collection costs; otherwise, the feedstock will come from plastic that is already collected for landfilling, not from the unmanaged waste bound for the ocean. Chemical conversion through pyrolysis is synergistic, not in competition with, mechanical recycling because each method handles different feedstocks. When used together, the economics of both are improved. Chemical conversion technology should only ever use feedstock that cannot be reduced, substituted, or mechanically recycled.
How can we use the model for national issues? Is it possible to do the modelling for specific countries?
The model is already being applied at the national level in Indonesia, Nigeria, and Vietnam under the public-private collaboration Global Plastic Action Partnership. It has also been applied in Germany and Sweden.
Was the local price of plastic considered (it differs from one country to another)?
The recyclate sale price was estimated by archetype (high income, upper middle income, lower middle income, and low-income countries) based on expert panel consensus. Plastic-to-fuel technologies were considered as a means of controlled disposal, not recycling.
Did you take into consideration different 'definitions of recycling' in different parts of the world?
Recycling technologies were split into 1) mechanical closed-loop recycling, 2) mechanical open-loop recycling, and 3) plastic-to-plastic chemical conversion systems that produce new packaging, products, or feedstock.
What needs to be done to ensure that substitutes do not result in negative environmental impact/consequences?
In most cases, Life Cycle Assessment studies suggest that substitution of single-use products by single-use products made of other materials is not a useful outcome. See the following report for more discussion on this issue: https://www.lifecycleinitiative.org/activities/key-programme-areas/technical-policy-advice/single-use-plastic-products-studies. Shifting to reuse schemes (which also need to be made possible) is more effective.
Most of the policies suggested seem to be national-level policies, what policies do you think could be applied at a global level through the proposed Treaty?
Plastics are international, and the connectivity of policy options will be critical. Certain policy directions will be universal – e.g., reduce and remove unnecessary and harmful plastics, reduce incineration. A global Treaty can also help to set the direction and goal(s) of national policies, with national policies aligning to the overall direction of the global goal. A Treaty can also help to set and support metrics, monitoring, common definitions, knowledge sharing, best practice, and a place to share learnings on what works and what doesn’t to tackle plastic pollution. The ultimate goal of the global agreement and policy and implementation measures will be negotiated over the coming two years.
