The impact of plastics on the environment-which everyone now associates with water, land and air pollution-also deserves to be considered from the perspective of greenhouse gas emissions into the atmosphere. At the current rates of growth in global demand for plastics, an emergency is in the offing. In recent scientific study, scenario analysis and strategies to be implemented.
Plastics and greenhouse gas emissions, 2020-2050 scenario
‘Strategies to reduce the global carbon footprint of plastics’. (1) The scientific study published in Nature Climate Change first considers greenhouse gas emissions, in the Life Cycle Assessment (LCA) of plastics materials. And their overall contribution to global Greenhouse Gases (GHG) emissions, so therefore to climate change:
– resin production is the stage where most emissions are produced (61 percent), particularly where virgin polymers are processed. This is followed by the conversion (30 percent) and ‘end-of-life’ (9 percent) stages, i.e., landfilling and incineration (calculated from 2015 data).
– 15 percent of greenhouse gas emissions (6.5 Gt CO2e) will come from this production sector alone–between now and 2050–if demand growth maintains the current pace (+4 percent, the annual average for the 2010-2015 period). A hitherto underestimated emergency, given that plastics are now attributed relatively small contributions to GHG emissions (3.5 percent, or 1.7 Gt CO2e, 2015).
Plastics and greenhouse gases, strategies
Researchers at the Bren School of Environmental Science and Management (University of California, Santa Barbara, USA) considered four strategies that could limit CO2 emissions related to the life cycle of plastics:
– Reduction in the growth rate of demand, from 4 percent to 2 percent annually,
– renewable energy. With assumptions of total decarbonization, with exclusive (100%) use of renewable energy by 2050,
– recycling. The most ambitious goal, paradoxically, is to reach 100 percent recycling in 2050 (completely excluding the still significant share of waste disposal),
– Replacement of plastics from fossil fuels with those derived from biological material. (so-called bioplastics).
Perspectives
The strategies identified envisage the following scenarios:
– reducing the growth trend in demand for plastics (from +4 to +2% per year) can reduce emission levels substantially. From -56% (with energy mix unchanged from present) to -81% (with only renewables), compared to the trajectory outlined to 2050,
– conversion to renewable energy alone can reduce 62% of plastics-related GHGs at unchanged rate of consumption growth. Contain emissions within current levels when coupled with reducing the demand growth trend . Decrease them, where then replace the raw materials with bio-based plastics,
– total recycling of plastic waste by itself would result in a quarter reduction in emissions (-25%),
– replacing petroleum plastics with plant-derived materials-although helpful in mitigatingpollution of seas, including the Mediterranean, water and air by microplastics-does not appear to have a significant impact on emission levels (2).
The synergy of the identified solutions-half demand growth, 100 percent renewable energy, and recycling-can enable the reduction of material life-cycle emissions. Minus 77, 84, 86%, respectively, on plastics from fossil fuels and bioplastics from corn and sugarcane.
– if all plastic waste were incinerated, greenhouse gas emissions would reach 8 Gt in 2050, 22% higher than the baseline (6.5 Gt). Whereas if all plastic waste were recycled, emissions in 2050 would be 4.9 Gt, 25 percent less than projected,
Criticality
The recycling rate (18 percent) is still decidedly low, compared to the volumes of global plastics production (4.07 million tons in 2015). And beyond the major commitments aired on a global scale-such as the ‘New Plastics Economy Global Commitment‘(NPEGC)-virgin polymers remain more advantageous, for operators, than those derived from recycling.
Therefore, the low cost of raw material from fossil fuels remains the primary cause of resistance to the ecological transition. And so it is that the operators in the supply chain (of production, processing and use of materials) must be called upon to cover the immense costs of plastics on the environment, which to date have been externalized onto communities. Effective tax policies, incentives for recycling facilities and technological innovation are needed.
The use of bioplastics is not in itself worth solving the waste problem, as their composting or incineration produces similar if not greater emissions than those emitted by hydrocarbon plastics. As well as calling for more selective recycling collection and special composting infrastructure. Moreover, the production of biopolymers, like that of ‘biofuels,’ cannot come based on agricultural raw materials diverted from food production. (3)
‘Our results indicate that the absolute reduction of lifecycle GHG emissions from plastics requires a combination of decarbonizing energy infrastructure, improving recycling capacity, adopting bio-based plastics, and managing demand. (1)
Dario Dongo and Alessandra Mei
Notes
(1) JiaJia Zheng, Sangwon Sush (2019). Strategies to reduce the global footprint of plastics. Nature Climate Change, 9, 374-378. https://doi.org/10.1038/s41558-019-0459-z
(2) EoL(End of Life) management of bio-based plastics, especially biodegradable plastics, requires systematic changes such as separate collection and recycling infrastructure. The inclusion of biodegradable plastics in the mixture of conventional plastic waste may indeed affect the quality of recyclates
(3) If the current demand for plastics were to be fully met by bioplastics, 250 million tons/year would be needed. And if biopolymers were derived from agricultural commodities-rather than by-products of their processing and mowing-it would take dedicating 5 percent of the planet’s cultivated land to their production. Exacerbating the current food security crisis. V. https://www.greatitalianfoodtrade.it/sicurezza/food-security-e-nutrizione-rapporto-fao-2019
Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.
Graduated in Law from the University of Bologna, she attended the Master in Food Law at the same University. You participate in the WIISE srl benefit team by dedicating yourself to European and international research and innovation projects.
