- Bioplastics, or plant-based plastics, are often promoted as a climate-friendly alternative to petroleum-based plastics. A recent study from the University of Bonn and published in published in the journal Environmental Research Letters suggests that shifting to bioplastics could have less positive effects than expected, and that increased consumption of bioplastics is likely to generate increased greenhouse gas emissions from cropland expansion on a global scale.
- Plastics are usually made from petroleum. The carbon embodied is suddenly released into the atmosphere by degradation or burning, contributing to global warming. Bioplastics, on the other hand, are in principle climate-neutral. Plants get carbon dioxide from the air through their leaves; producing bioplastics therefore consumes carbon dioxide, which compensates for the amount that is later released. Overall, their net greenhouse gas balance is assumed to be zero.
- The new study suggests that with the current level of technology, this issue is probably not as clear as often assumed.
- The production of bioplastics in large amounts would change land use globally. This could potentially lead to an increase in the conversion of forest areas to arable land. However, forests absorb considerably more carbon dioxide than maize or sugar cane annually.
- The area of land used for agriculture increases in the tax scenario, while the forest area decreases by 0.17%. This translates into enormous quantities of carbon dioxide being emitted into the atmosphere.
- This is considered to occur as a one-time effect. Nevertheless, according to our calculations, it will take more than 20 years for it to be offset by the savings achieved by fossil substitution.”