Chinese scholars and overseas collaborators have made new progress in the research on the mechanism of atmospheric methane concentration growth

Figure Attribution
of accelerated growth in atmospheric methane concentrations in 2020.
Attribution of (a) accelerated growth in atmospheric methane concentrations in 2020 compared to 2019; (b) Spatial patterns of changes in methane emissions based on "top-down" atmospheric inversion methods; (c) Spatial patterns of dominant sources of change in methane emissions in 2020; (d) Spatial patterns of changes in methane emissions estimated by the "bottom-up" approach

With the support of the National Natural Science Foundation of China (grant numbers: 41722101, 41830643), researcher Peng Shushi of Peking University and overseas collaborators have recently made new progress
in the research of the mechanism of atmospheric methane concentration growth 。 The study, titled "Wetland emission and atmospheric sink changes explain methane growth in 2020," was published in the journal Nature on December 15
, 2022 。 Link to the paper: _istranslated="1">.

Methane is an important greenhouse gas
.
Since the Industrial Revolution, the concentration of methane in the atmosphere has increased 2-fold
.
In order to achieve the Paris Agreement's greenhouse gas reduction targets, the task of reducing the rate of anthropogenic methane emissions to reduce atmospheric methane concentrations is urgent
.
Notably, atmospheric methane concentrations have accelerated over the past fifteen years, reaching their highest
level since site observations began in 1984 in 2020.
Therefore, how to analyze the mechanism of the recent acceleration of atmospheric methane concentration has become an important problem
in international global climate change research.

The growth rate of atmospheric methane concentration is mainly controlled
by anthropogenic emissions, natural source emissions and atmospheric sinks.
However, the uncertainty of these three estimates makes attribution studies of atmospheric methane concentration growth difficult
.
In 2020, due to the impact of the new crown epidemic prevention and control measures in various countries, the total anthropogenic methane emissions decreased, but the atmospheric methane concentration soared, which provided a perfect "experiment"
for controlling anthropogenic emissions to study the attribution of changes in atmospheric methane concentrations.

In the face of the above opportunities and challenges, researcher Peng Shushi of Peking University and overseas collaborators combined "bottom-up" and "top-down" greenhouse gas source and sink assessment methods and multi-source data to clarify the mechanism
of atmospheric methane concentration soaring in 2020.
It was found that the warmer and wetter climate in 2020 led to an increase in methane emissions from natural wetlands in the northern hemisphere, contributing half
of the increase in atmospheric methane concentrations.
As the reduction in anthropogenic nitrogen oxide emissions caused by the pandemic reduced the concentration of atmospheric OH radicals, thereby contributing the other half of the increase in atmospheric methane concentration in 2020 (Figure), future methane reduction plans need to consider changes
in atmospheric methane concentrations caused by anthropogenic pollutants such as nitrogen oxides.

The study not only provides new insights into understanding the global methane budget, but also provides a scientific basis
for meeting the goals of the Paris Agreement and global methane reduction commitments 。 The journal Nature published a review article entitled "Cause of the 2020 surge in atmospheric methane clarified" by renowned scholar Professor George H.
Allen, which gave a positive review ( _istranslated="1"> of the study.