DAILY SCIENCE

Paper recycling isn’t necessarily good for the climate
Global paper consumption is rising, and recycling paper uses more fossil fuels than virgin paper. But a switch to renewable energy and better wastepaper disposal practices could drastically cut carbon emissions.
October 22, 2020

Recycling is one of the easiest things consumers can do to tread lighter on the environment. But much depends on the material being recycled. A new modeling study shows that greenhouse gas emissions would increase by 2050 if we recycled more paper.

If all wastepaper was recycled, emissions could increase by 10%, researchers report in the Nature Sustainability study. That’s because recycling paper uses more fossil fuel electricity than making new paper. The emissions would drastically go down if paper production and recycling were powered by renewable energy.

“The recycling of some materials, for instance metals, can lead to a very large reduction in emissions,” said Paul Ekins of University College London’s Institute for Sustainable Resources in a press release. “But we need to be careful about assumptions that recycling, or a circular economy in general, will always have a positive effect on climate change.”

Rising demand for packaging is likely going to increase the global use of paper and paperboard, especially given the push to substitute paper for plastics, the researchers say. Just like for any other material, producing and recycling paper requires energy. But paper is unique in some ways. While making new paper from trees requires more energy than recycling paper, the energy for virgin paper production is generated from the by-product of the wood pulping process. Paper recycling, by contrast, uses electricity from the grid.

Ekins and his colleagues first estimated the emissions from the global paper life cycle for 2012. To do this they calculated the carbon emissions due to electricity and fuel use from forestry and mining, pulping, paper making and printing. They also calculated the emissions from paper waste that goes to landfill. Paper made up for 1.3% of global greenhouse gas emissions, or 721 metric tons of carbon dioxide equivalent. Roughly a third of these emissions arise from landfilled paper products.

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The researchers then modeled how emissions would change up to 2050 with changes in levels of recycling, energy use, and landfill practices. If things continued as usual, paper-related emissions would increase to 736 metric tons of carbon dioxide equivalent by 2050. In a scenario where recycling efforts are more ambitious but landfill and energy use stays on the same path, emissions would go up by 10% to 808 metric tons.

But in a more radical scenario with modern landfill practices such as capturing methane and using it for energy would reduce emissions to 591 metric tons. But switching to renewable energy has the biggest impact, even with recycling and landfill practices remaining on the same path: renewables would reduce emissions by 96% to 28 tons.

The results indicate that at least for paper, a circular use of materials cannot guarantee reducing emissions, and that decarbonizing the energy supply is essential to meet climate change targets. “Increased recycling and recovery is not a straightforward recipe for reducing global greenhouse gas emissions,” the researchers write. “In our analysis, landfill practices mattered more than material flows, and energy use mattered the most.

Source: Stijn van Ewijk, Julia A. Stegemann and Paul Ekins. Limited climate benefits of global recycling of pulp and paper. Nature Sustainability, 2020.

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