Trees versus methane – the role of forests in the fight against greenhouse gases

Methane and global warming

Methane is a potent greenhouse gas that has been responsible for about 30% of global warming since pre-industrial times, and its emissions are now rising faster than ever since measurements began in the 1980s.

So far, it is the soil that has been considered Earth’s only methane sink. However, a new study published July 24 in Nature Nature shows that it is the trees that may be just as important, if not more so, in terms of methane reduction.

The positive impact of trees on the climate has long been known to science, and the aforementioned study, conducted by an international team of scientists led by the University of Birmingham, has revealed another rather surprising benefit of trees for the climate.The analysis performed proved that microbes living either in the bark or in the wood itself remove atmospheric methane on a scale equal to or even greater than the soil.

„The Global Methane Commitment, launched in 2021 at the COP26 climate summit, aims to reduce methane emissions by 30% by the end of the decade.Our results suggest that planting more trees and reducing deforestation are certainly important elements in achieving this goal “the study was summarized by Professor Vincent Gauci of the University of Birmingham, chief scientist of the research team.

In what area was methane absorption most effective?

Tropical, temperate zone and boreal forests were analyzed. Special attention was paid to tropical forests in the Amazon and Panama, deciduous forests in Wytham Woods in Oxfordshire, UK, and boreal coniferous forests in Sweden.

They found that methane uptake was strongest in tropical forests, probably because the microbes thrive in warm, humid conditions. The newly discovered methane absorption process increases the climate benefits provided by temperate and tropical trees by about 10% on average.

By studying the exchange of methane between the atmosphere and the bark of trees at different heights, it was possible to show that while at soil level the trees probably emit a small amount of methane, from a few meters up the direction of exchange changes and methane from the atmosphere is absorbed.

The team used laser scanning methods to quantify the total global area of forest tree bark. Preliminary calculations showed that the total global tree contribution ranges from 24.6 to 49.9 Tg (million tons) of methane.

In addition, analysis of the shape of the trees shows that if all the bark of all the trees in the world were laid flat, its surface area would be equal to the Earth’s land area.

Professor Gauci and colleagues in Birmingham are now planning a new research program to find out whether deforestation has led to an increase in atmospheric methane concentrations. They also aim to better understand the microorganisms themselves, the mechanisms used to absorb methane, and to investigate whether the removal of methane from the atmosphere by trees can be increased.

_Source:

_{https://www.nature.com/articles/s41586-024-07592-w}