The impact of plastic on the environment – which everyone now associates with pollution of water, land, and air – deserves to be considered also from the perspective of greenhouse gas emissions into the atmosphere. At the current rates of growth in global plastic demand, an emerging emergency is looming. In a recent scientific study, the scenario analysis and strategies to implement.
Plastic 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 primarily considers greenhouse gas emissions, in the Life Cycle Assessment (LCA) of plastic materials. And their overall contribution to global emissions of Greenhouse Gases (GHG), thus to climate change:
– resin production is the phase in which the most emissions (61%) are produced, especially when virgin polymers are processed. Followed by conversion phases (30%) and end-of-life (9%), that is landfill disposal and incineration (calculation based on 2015 data).
– 15% of emissions of greenhouse gases (6.5 Gt CO2e) will derive from this production sector alone – by 2050 – if demand growth maintains the current pace (+4%, the annual average during 2010-2015). An emergency so far underestimated, given that plastics are currently attributed relatively modest contributions to GHG emissions (3.5%, equal to 1.7 Gt CO2e, 2015).
Plastics and greenhouse gases, strategies
The researchers of 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 plastic:
– reduction of the growth rate of demand, from 4% to 2% per year,
– renewable energy. With the hypothesis of total decarbonisation, with exclusive use (100%) of renewable energy by 2050,
– recycling. The most ambitious objective, paradoxically, is to reach 100% recycling in 2050 (completely excluding the still significant share of waste disposal),
– replacement of plastics from fossil fuels with those derived from biological material. (CD. bioplastics).
Perspectives
The strategies identified the following scenarios arise:
– the reduction of trend growth in demand for plastic (from +4 to +2% per year) can reduce emissions levels substantially. From -56% (with the energy mix unchanged compared to the present) to -81% (with renewable energy only), compared to the trajectory outlined for 2050,
– conversion renewable energy alone can reduce 62% of GHGs linked to plastics, with an unchanged rate of growth in consumption. Contain emissions within current levels, if combined with reduction of trend of growth in demand. Reduce them, where the raw materials are then replaced with bio-based plastics,
– recycling total plastic waste in itself would allow a reduction of a quarter of emissions (-25%),
– replacement of plastic from oil with materials of vegetal origin - although useful for mitigating the pollution of seas, including the Mediterranean, water and air from microplastics - does not appear to have a significant impact on emission levels (2).
The synergy of the solutions identified - halved growth in demand, 100% renewable energy and recycling - can make it possible to reduce emissions linked to the life cycle of materials. Minus 77, 84, 86%, respectively, on plastic from fossil fuels and bioplastics from corn and sugar cane.
– if all plastic waste were incinerated, in 2050 greenhouse gas emissions would reach 8 Gt, 22% more than the baseline data (6.5 Gt). Whereas if all plastic waste were recycled, emissions in 2050 would be 4.9 Gt, 25% less than expected,
Critical issues
The recycling rate (18%) is still decidedly low, compared to the global volume of plastic production (4.07 million tons in 2015). And beyond the major commitments proposed globally – such as the ‘New Plastics Economy Global Commitment’ (NPEGC) – virgin polymers remain more advantageous, for operators, than those derived from recycling.
The low cost of raw materials from fossil fuels therefore remains the primary cause of resistance to the ecological transition. And this is why operators in the supply chain (production, transformation and use of materials) must be called upon to cover the enormous costs of plastic on the environment, which are still outsourced to communities. We need effective tax policies, incentives for recycling plants and technological innovation.
The use of bioplastics does not by itself solve the waste problem, as their composting or incineration produces emissions similar to or even higher than those emitted by hydrocarbon-based plastics. In addition, they require more selective waste sorting and special composting infrastructure. The production of biopolymers, like that of ‘biofuels,’ cannot be based on agricultural raw materials diverted from food production. (3)
‘Our results indicate that the absolute reduction of GHG emissions in the life cycle of plastic materials requires a combination of decarbonization of energy infrastructures, improvement of recycling capacity, adoption of bio-based plastics, and demand management.’ (1)
Dario Dongo e 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) The End of Life (EoL) management (End of Life) of bio-based plastics, particularly biodegradable ones, requires systemic changes such as separate collection and recycling infrastructure. The inclusion of biodegradable plastics in the conventional plastic waste stream can indeed affect the quality of recyclates
(3) If the current demand for plastic were to be fully met by bioplastics, 250 million tons/year would be needed. And if biopolymers were derived from commodities agricultural – instead of by-products of their processing and mowing – it would be necessary to dedicate 5% of the cultivated land on the planet to their production. With aggravation of the current crisis of food security.
Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT – Food Times) and Égalité.
Graduate in Law from the University of Bologna, she attended the Master in Food Law at the same University. She is part of the WIISE srl benefit team, dedicated to European and international research and innovation projects.
