The Greenhouse Gas Implications of Plastics and the Circular Bioeconomy

A plastics module, including waste and end-of-life options, was built into the IMAGE model to investigate four scenarios for the global plastic sector. These showed that a high price for greenhouse gas emissions, meeting the Paris Climate Accord’s two-degree goal, is not enough in itself to encourage the plastic sector to switch from fossil feedstocks to bio-based raw materials and a circular economy. Climate policy may even lead to more plastic landfilling, as it avoids CO2 emissions and is cheaper than other forms of waste treatment. A scenario with more policies geared towards a circular plastic sector (including stricter requirements for product design and standardisation of plastic types) would greatly increase the recycling of plastic waste, lower resource consumption, and further reduce the CO2 emissions of the plastic sector until 2050, while preventing large-scale disposal in landfills. However, solely aiming for circularity would limit further emission reductions in the second half of the century, because the role of plastic for biogenic (and therefore non-fossil) carbon storage is underutilised. Moreover, there is not enough plastic waste available to meet the growing plastic demand via recycling. Therefore, a fully circular plastic sector is only possible if demand for plastics is curbed.

A combination of bio-based raw materials with emissions-free electricity, high-quality recycling and a minimisation of waste incineration could potentially turn the sector into a carbon sink. By 2050, 13% of the biomass currently used to generate energy could be utilised as a raw material for plastics. Plastics with a long service life, such as building materials, represent the largest stock of plastic on earth. Producing these materials from bio-based raw materials would result in net negative emissions.