Trees Absorb Methane

The article below is excerpted from the research cited below and the Global Carbon Project.

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 

Methane is a powerful greenhouse gas that traps heat 28 times more effectively than carbon dioxide over a 100-year timescale. After carbon dioxide, methane is responsible for about 26% of climate change. Concentrations of methane have increased by more than 150% since industrial activities and intensive agriculture began.

Methane is produced under conditions where little to no oxygen is available. About 30% of methane emissions are produced by wetlands, including ponds, lakes and rivers. Another 20% is produced by agriculture, due to a combination of livestock, waste management and rice cultivation. Activities related to oil, gas, and coal extraction release an additional 30%. The remainder of methane emissions come from minor sources such as wildfire, biomass burning, permafrost, termites, dams, and the ocean.

It is known that trees growing in wetlands emit methane that was generated in the wetland. It is also known that methane eating microbes live on tree bark. These microbes are called methanotrophs and consume methane as their source of energy. In the study cited above Vincent Gauci and his team took measurements of the exchange rate of methane between the atmosphere and the tree bark. To their surprise they found that while most trees emit small amounts of methane at ground level, but as they move up the tree trunk, the exchange of methane with the atmosphere reverses.

They found that once you get to about two meters above the forest floor methane uptake, can dominate the net ecosystem contribution of trees. Trees are on net a methane sink. The scientists findings indicate that the climate benefits of tropical and temperate forest protection and reforestation may be greater than previously assumed. They estimate that in tropical locations trees absorbed about 12% CO2 equivalent emissions once the methane absorbed is factored into the models. In more temperate climate conditions the improvement is less- about 7%. Our existing forest are far more important to our planet than previously thought. Maintaining and restoring our forest is essential, but we need to know more about our forested ecosystems. More research is needed on the atmospheric interactions of tree canopies. The focus should be on not only restoring woods and planting trees, but also preserving current forests. tree planting makes more sense for some areas than others, preserving forests also means removing trees to help prevent forest fires and to help forests better survive in the long run.

Harvard University has announced that they are now accepting applications for the Bullard Fellowships. Harvard University awards a limited number of Bullard Fellowships annually to individuals pursuing a variety of approaches to the study of forested ecosystems. Starting this year, Bullard Fellowships may be awarded as “Short-Term” fellowships (2-3 months) or “Long-Term” fellowships (6 to 12 months) to enable more professionals in the field to pursue the fellowship.

A major goal of the Bullard Fellowship program is to enhance research activities at Harvard Forest and build long-term collaborations that connect Harvard Forest with other parts of the University. Fellows can be based at the Harvard Forest or associated with other departments and centers at Harvard, such as the Department of Organismic and Evolutionary Biology, the Salata Institute for Climate and Sustainability, and the Arnold Arboretum. Bullard Fellowships are not intended for post-doctoral fellows; instead they are targeted at individuals with a record of independent scholarship and professional accomplishment.

Applications will open August 1, 2024 for fellowship opportunities in 2025-2026.

The deadline for applications is October 1, 2024.

Charles Bullard Fellowship in Forest Research | Harvard Forest