An international study published in Nature reveals that seasonal variations in atmospheric methane vary from one region of the globe to another. While the seasonal amplitude of methane decreases in high northern latitudes, it increases in tropical and subtropical regions. These trends provide valuable clues as to the evolution of methane sources and sinks on a global scale. At the heart of this scientific breakthrough are the contributions of Philippe Ciais, Xin Lin, Didier Hauglustaine and Yi Xi from the Laboratoire des Sciences du Climat et de l’Environnement (LSCE). Thanks to their expertise in atmospheric modelling and atmospheric chemistry, the Franco-Chinese team from Peking University and LSCE has been able to attribute these trends to the combined effects of global warming and changes in atmospheric chemistry.
Simulations carried out with the GEOS-Chem and LMDZ-INCA models have shown that: the increase in natural methane emissions from Arctic wetlands, favored by a warmer, wetter climate, attenuates the seasonal methane cycles in these regions.
Conversely, in tropical zones, the intensification of cycles is mainly due to an increase in the concentration of the hydroxyl radical (OH), the main agent for destroying methane in the atmosphere.
This study underlines the importance of continuing efforts to reduce methane emissions if we are to meet the climate targets set by the Paris Agreement.
It also highlights the central role played by LSCE in understanding global climate change.
Référence :
Liu, G., Shen, L., Ciais, P. et al. Trends in the seasonal amplitude of atmospheric methane. Nature 641, 660–665 (2025).
https://doi.org/10.1038/s41586-025-08900-8
Contacts LSCE : Philippe Ciais