New modelling suggests that greenhouse-gas emissions would increase by 2050 if more paper is recycled, as current methods rely on fossil fuels and electricity from the grid.
Researchers modelled various scenarios for increasing recycling of wastepaper by 2050 and the impact this would have on greenhouse emissions.
The study looked at how different levels of recycling, renewable energy use and more environmentally friendly landfill practices might affect our ability to reduce emissions in line with a target to avoid a 2° Celsius temperature rise by 2050.
They found that if all wastepaper was recycled, emissions could increase by 10 per cent, as recycling paper tends to rely more on fossil fuels than making new paper does.
Under current trends, emissions are expected to rise from the 2012 level of 721 metric tonnes of carbon dioxide equivalent in a year to 736 metric tonnes in 2050, with efforts to reduce emissions outweighed by increased demand for paper.
However, the researchers also found that emissions from the paper industry would be substantially reduced if production and disposal were carried out using renewable energy sources rather than fossil fuels.
Making new paper from trees requires more energy than paper recycling, 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.
The researchers found that modernising landfill practices, for example by capturing methane emissions and using them for energy, also had a positive effect - although not as profound as moving to renewables.
Dr Stijn van Ewijk, the lead author of a paper reporting results of the research, 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. 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."
Senior author Professor Paul Ekins added: "The recycling of some materials, for instance metals, can lead to a very large reduction in emissions. 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."
The researchers emphasised that recycling has benefits beyond combatting global warming including the conservation of resources which remains critical for sustainability.
Paper accounted for around 1.3 per cent of global greenhouse-gas emissions in 2012, with about a third of these emissions coming from the disposal of paper in landfills. The use of paper is expected to rise in the coming years as the move away from plastics leads to increased demand for paper packaging.
Auditors recently warned that the EU is at risk of missing its plastic packaging recycling targets and that an incoming ban on exports of trash to poorer nations will increase the likelihood of a plastic waste pile-up.
