A new study published in Nature Sustainability by a teams of researchers at the prestigious Swiss university ETH Zurich demonstrates that the impact of plastics production on human health and climate is greater than hitherto assumed. The team’s findings, based on a careful analysis of the global plastics value chain, reveal that coal-fired power plants contribute far more heavily to the carbon footprint of plastics materials than thought, mainly due to an increased use of coal for process heat, electricity and as a raw material in production.
To date, most research into the global environmental impact of plastics has been primarily focused on the disposal phase, with only a handful of studies examining the impact of plastics production on, for example, climate and air quality. To do so requires detailed information about supply chains and processes in order to be able to trace all relevant material and energy flows.
“So far, the simplistic assumption has been that the production of plastics requires roughly the same amount of fossil resources as the amount of raw materials contained in plastics – particularly petroleum,” said Livia Cabernard, a doctoral student at the Institute of Science, Technology and Policy (ISTP) at ETH Zurich. As a result, the relative significance of production versus disposal has been significantly underestimated.
Cabernard is part of a team of researchers led by Stephan Pfister, Senior Scientist at the ISTP, and Stefanie Hellweg, ETH Professor of Ecological Systems Design at the Institute of Environmental Engineering, that has painstakingly analysed the climate and health impact of the global plastics supply chain over the two decades from 1995 to 2015. The researchers calculated the greenhouse gas emissions generated across the plastics’ life cycle, from fossil resource extraction, to processing into product classes and use, through to end of life, including recycling, incineration and landfill. They used a new method for their study developed by Cabernard, involving a multi-regional, input-output analysis that accurately maps global supply chains from production to consumption across industries, countries and regions. According to their findings, the global carbon footprint of plastics has doubled since 1995, reaching 2 billion tonnes of CO2 equivalent (CO2e) in 2015. This represents 4.5 percent of global greenhouse gas emissions, and is more than previously thought.
The team identified the fast-expanding plastics production activities in coal-based, newly industrialised countries such as China, India, Indonesia and South Africa as the main cause of the growing carbon footprint of plastics. “The plastics-related carbon footprint of China’s transport sector, Indonesia’s electronics industry and India’s construction industry has increased more than 50-fold since 1995,” Cabernard said.
The energy and process heat needed for the production of plastics in these countries comes primarily from the combustion of coal. A small amount of coal is also used as a raw material for plastics. Globally, coal-based emissions from plastics production have quadrupled since 1995 and now account for nearly half of the global carbon footprint of plastics.
The issue with coal is that, when coal is burned, it produces extremely fine particles that accumulate in the air. These have been shown to be able to cause asthma, bronchitis and cardiovascular disease. As more and more coal is used for process heat and electricity, and as a raw material in the production of plastics materials, the negative effects on health also escalate.This study shows that in the period from 1995-2015 the global health footprint of plastics from fine particulate air pollution increased by 70 percent, causing approximately 2.2 million disability-adjusted life years (DALYs) in 2015.
Cabernard L, Pfister S, Oberschelp C, Hellweg S: Growing environmental footprint of plastics driven by coal combustion. Nature Sustainability (2021), published online 2 December, doi: 10.1038/s41893-021-00807-2