A circular economy is expected to achieve sustainability goals through efficient use and reuse of materials. Waste recycling is an important part of a circular economy. However, for some materials, the potential environmental benefits of recycling are unclear or contested. The study, published in Nature Sustainability, found that greenhouse gas emissions would increase by 2050 if we recycled more paper, as current methods rely on fossil fuels and electricity from the grid.
The team modelled several conditions to increase wastepaper recycling by 2050 and the impact this would have on greenhouse gas emissions. They learned that if all wastepaper was recycled, emissions could surge by 10%, as recycling paper depends more on fossil fuels than making new paper. However, the team discovered that emissions would drastically decrease if paper production and disposal were performed using renewable energy sources instead of fossil fuels.
Making new paper from trees uses more energy than recycling it. But the energy for this process is generated from black liquor, the low-carbon by-product of the wood pulping process. In contrast, paper recycling relies on fuels and electricity from the grid. That’s the main concern of researchers, leading to emissions.The team found that modernizing landfill practices can have a positive effect, such as capturing methane emissions and using them for energy. Nevertheless, the effect isn’t as significant as moving to renewables, they argued. Recycling isn’t helpful unless it’s powered by clean energy sources.
Lead author Dr Stijn van Ewijk (UCL Institute for Sustainable Resources and Yale Center for Industrial Ecology) said: Our study shows that recycling is not a guaranteed way to address climate change. Recycling of paper may not be helpful unless it is powered by renewable energy. We looked at global averages, but trends may vary considerably in different parts of the world. Dr van Ewijk continued, “Our message isn’t to stop recycling, but to point out the risk of investing in recycling at the expense of decarbonising the energy supply and seeing very little change to emissions as a result.”
If past trends continue, emissions would slightly increase from the 2012 level (721 metric tons of carbon dioxide equivalent in a year) to 736 metric tons in 2050, the findings showed. A recycling program, with landfill and energy uses remaining on the same path, would increase this still further by 10% (to 808 metric tonnes).
Researchers explained that, while paper recycling can save trees and protect forest carbon stocks, the extent of this is unknown. This is because of a lack of understanding of the global forest carbon stock and the interrelated causes of deforestation. The analysis, therefore, assumes that recycling neither harms nor benefits forests.
