| Titre : | Wetland emission and atmospheric sink changes explain methane growth in 2020 (2022) |
| Auteurs : | Shushi Peng, Auteur ; Xin Lin, Auteur ; Rona L. Thompson, Auteur ; Yi Xi, Auteur ; Gang Liu, Auteur ; Didier Hauglustaine, Auteur ; Xin Lan, Auteur ; Benjamin Poulter, Auteur ; Michel Ramonet, Auteur ; Marielle Saunois, Auteur ; Yi Yin, Auteur ; Zhen Zhang, Auteur ; Bo Zheng, Auteur ; Philippe Ciais, Auteur |
| Type de document : | Article |
| Dans : | Nature (612(7940) December, 2022) |
| Article en page(s) : | 477-482 |
| Langues: | Anglais |
| Mots-clés : | Zone humide ; Méthane ; Impact activités humaines |
| Résumé : | Atmospheric methane growth reached an exceptionally high rate of 15.1 ± 0.4 parts per billion per year in 2020 despite a probable decrease in anthropogenic methane emissions during COVID-19 lockdowns. Here we quantify changes in methane sources and in its atmospheric sink in 2020 compared with 2019. We find that, globally, total anthropogenic emissions decreased by 1.2 ± 0.1 teragrams of methane per year (Tg CH4 yr−1), fire emissions decreased by 6.5 ± 0.1 Tg CH4 yr−1 and wetland emissions increased by 6.0 ± 2.3 Tg CH4 yr−1. Tropospheric OH concentration decreased by 1.6 ± 0.2 per cent relative to 2019, mainly as a result of lower anthropogenic nitrogen oxide (NOx) emissions and associated lower free tropospheric ozone during pandemic lockdowns2. From atmospheric inversions, we also infer that global net emissions increased by 6.9 ± 2.1 Tg CH4 yr−1 in 2020 relative to 2019, and global methane removal from reaction with OH decreased by 7.5 ± 0.8 Tg CH4 yr−1. Therefore, we attribute the methane growth rate anomaly in 2020 relative to 2019 to lower OH sink (53 ± 10 per cent) and higher natural emissions (47 ± 16 per cent), mostly from wetlands. In line with previous findings, our results imply that wetland methane emissions are sensitive to a warmer and wetter climate and could act as a positive feedback mechanism in the future. Our study also suggests that nitrogen oxide emission trends need to be taken into account when implementing the global anthropogenic methane emissions reduction pledge. |
| En ligne : | https://www.nature.com/articles/s41586-022-05447-w |



