For the first time, a team from the University of Birmingham describe how tree bark can remove methane gas from the atmosphere. The study was published in Nature.
Trees have been known to remove carbon dioxide from the atmosphere, but new research reveals a new and surprising benefit: Microbes in the tree bark cabin absorb methane, a powerful greenhouse gas.
A team of researchers from the University of Birmingham, UK, has shown that the microbes living in the bark can eliminate methane on a scale at least equal to that of the soil. This newly discovered process makes trees 10% more beneficial for climate overall than previously thought.
Methane is responsible for about 30% of global warming, and emissions have risen faster than ever since records began in the 80s. Until now, it was believed that most methane was removed by processes in the atmosphere and the rest by bacteria in the soil, but these results show that trees are important, too.
“The main ways in which we consider the contribution of trees to the environment is through absorbing carbon dioxide through photosynthesis and storing it as carbon. However, these results show a remarkable new way trees provide a vital climate service,” said Professor Vincent Gauci of the University of Birmingham. “The Global Methane Pledge, launched in 2021 at the COP26 climate change summit, aims to cut methane emissions by 30% by the end of the decade. Our results suggest that planting more trees and reducing deforestation surely must be important parts of any approach towards this goal.”
For this study, the team investigated different types of trees from tropical, temperate, and boreal forests, including the Amazon and Panama; temperate broadleaf trees in Wytham Woods, Oxfordshire, UK; and boreal coniferous forest in Sweden. The results showed that methane absorption was strongest in the tropical forests, most likely because microbes thrive in warm, wet conditions. On average, the new process adds around 10% to the climate benefit of temperate and tropical trees.
The team also used laser scanning methods to quantify the overall bark area, with preliminary calculations indicating that trees can eliminate between 24.6-49.9 Tg (millions of tonnes) of methane.
Curiously, if all the bark of the world’s trees were laid flat, the area would equal the Earth’s land surface. “Tree woody surfaces add a third dimension to the way life on Earth interacts with the atmosphere, and this third dimension is teeming with life and surprises, ” said co-author Yadvinder Malhi of the University of Oxford.
In the future, the team wants to assess if deforestation has caused increased atmospheric methane concentrations. They also aim to understand more about the microbes themselves, the mechanisms used to take up the methane, and whether this atmospheric methane removal by trees can be enhanced.
Gauci, V., Pangala, S.R., Shenkin, A. et al. Global atmospheric methane uptake by upland tree woody surfaces. Nature 631, 796–800 (2024). https://doi.org/10.1038/s41586-024-07592-w