The Carbon Footprint of Plastic Is Way Higher Than We Thought

Production of plastic is growing in Asia and it is all powered by coal.

Petrochemicals in scotland
Petrochemical plant in Scotland.

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Plastics are a pernicious producer of greenhouse gases. We have called them a solid fossil fuel, noting that making a kilogram of plastic emits 6 kilograms of carbon dioxide (CO2). When measuring my plastic usage while writing my book, "Living the 1.5 Degree Lifestyle," I counted 6 grams of CO2 for each gram of plastic. Estimates of total greenhouse gas emissions vary: The Center for International Environmental Law (CIEL) put it at 860 million metric tons in 2019 while research at the University of Santa Barbara calculated full life-cycle emissions, including incineration, at about 1.7 billion metric tons. Most of these emissions come from the use of fossil fuels as feedstocks for the making of plastics.

But a new study published in Nature Sustainability, "Growing environmental footprint of plastics driven by coal combustion," finds the footprint is even higher than previously thought. Researchers at ETH Zurich now estimate the full life-cycle emissions are now over 2 billion metric tons of carbon dioxide equivalents (CO2e) and represent 4.5% of global greenhouse gas emissions.

The major driver of the increase is the increase in production in China, India, and Indonesia, where the heat and electricity used in resin production are made with coal. The feedstock emissions are around what the CIEL calculated at 890 million metric tons, but twice as much fossil fuel (1.7 billion metric tons) was burned as fuel for plastic production as was contained in the feedstock.

This is all considerably higher than the previous University of Santa Barbara study by Jiajia Zheng and Sangwon Suh. ETH Zurich doctoral student Livia Cabernard said in a press release: “This study underestimated greenhouse gas emissions, however, because it did not take into account the increasing dependence on coal due to the outsourcing of production processes to coal-​based countries.”

The study also found that burning all that coal to make plastics increased particulate emission, causing about 2.2 million disability-adjusted life years (DALYs)– the number of years of life lost due to ill-health, disability, or death. So plastics are not only contributing to climate change, they are killing us with the emissions. The study authors conclude:

"This study highlights the need for improved policy measures to reduce the increasing carbon footprint of plastics production, which bears the major share of the plastics-related GHG emissions (even in a worst-case scenario where all plastics would be incinerated)... Our results underscore the importance of ongoing initiatives to reduce primary plastics production by avoiding, reusing, and recycling plastics as discussed in the context of the circular economy. Efficient measures include phasing out coal, transitioning to renewables and improving the energy efficiency in the plastics production process."

The study authors also make clear that rich countries can't keep offshoring their emissions to countries that make even dirtier plastics.

"As shown here for the past and future, decreasing the emissions in high-income regions as specified in the Paris Agreement is not sufficient. Such an approach even fosters a shift of plastics production to emerging regions with less-stringent environmental policies and limited economic power to implement state-of-the-art low-carbon technology. Thus, it is important that high-income regions invest in clean energy production throughout the supply chain."
Plastic uses

Livia Cabernard et al.

The study authors suggest that "a general ban on plastics is counterproductive as alternative materials often have higher environmental impacts." However in their value chain analysis, they show where it goes, and general bans could certainly be targeted at single-use plastics and packaging. The petrochemical industry has been on an expansion binge, hoping that a pivot to plastic will soak surplus fossil fuels, but we have to stop buying what they are selling.

The CIEL recommends "high-priority actions that would meaningfully reduce greenhouse gas emissions from the plastic lifecycle and also have positive benefits for social or environmental goals." These include:

  • Ending the production and use of single-use, disposable plastic
  • Stopping development of new oil, gas, and petrochemical infrastructure
  • Fostering the transition to zero-waste communities
  • Implementing extended producer responsibility as a critical component of circular economies
  • Adopting and enforcing ambitious targets to reduce greenhouse gas emissions from all sectors, including plastic production

And we might add in the holiday season, stop buying plastic junk.

And as for that estimate of 6 grams of carbon for each gram of plastic? Dividing the 2.59 billion metric tons of CO2 from the new study by the 380 million metric tons of plastic produced in 2015, I get 6.8 grams of CO2, which I will round up to 7 grams.

View Article Sources
  1. "Plastic Bags and Plastic Bottles – CO2 Emissions During Their Lifetime." Time For Change.

  2. "Plastic & Climate: The Hidden Costs of a Plastic Planet." Center for International Environmental Law, 2019.

  3. Zheng, Jiajia, and Sangwon Suh. "Strategies to Reduce the Global Carbon Footprint of Plastics." Nature Climate Change, vol. 9, no. 5, 2019, pp. 374-378., doi:10.1038/s41558-019-0459-z

  4. Cabernard, Livia, et al. "Growing Environmental Footprint of Plastics Driven by Coal Combustion." Nature Sustainability, 2021, doi:10.1038/s41893-021-00807-2