Boreal–Arctic wetland methane emissions modulated by warming and vegetation activity

• Published in: Nature climate change 2024, Vol.14 (3), p.282-288
• Main Authors: Yuan, Kunxiaojia, Li, Fa, McNicol, Gavin, Chen, Min, Hoyt, Alison, Knox, Sara, Riley, William J., Jackson, Robert, Zhu, Qing
• Format: Article
• Language: English
• Subjects: 704/106; 704/47; Annual variations; Arctic zone; Climate Change; Climate Change/Climate Change Impacts; Climate feedback; Earth and Environmental Science; Eddy covariance; Emissions; Environment; Environmental Law/Policy/Ecojustice; ENVIRONMENTAL SCIENCES; Ice environments; Interannual variability; Interannual variations; Lowlands; Machine learning; Methane; Methane emissions; Observational learning; Temperature anomalies; Vegetation; Wetlands
• ISSN: 1758-678X; 1758-6798
• DOI: 10.1038/s41558-024-01933-3

Wetland methane (CH 4 ) emissions over the Boreal–Arctic region are vulnerable to climate change and linked to climate feedbacks, yet understanding of their long-term dynamics remains uncertain. Here, we upscaled and analysed two decades (2002–2021) of Boreal–Arctic wetland CH 4 emissions, representing an unprecedented compilation of eddy covariance and chamber observations. We found a robust increasing trend of CH 4 emissions (+8.9%) with strong inter-annual variability. The majority of emission increases occurred in early summer (June and July) and were mainly driven by warming (52.3%) and ecosystem productivity (40.7%). Moreover, a 2 °C temperature anomaly in 2016 led to the highest recorded annual CH 4 emissions (22.3 Tg CH 4  yr −1 ) over this region, driven primarily by high emissions over Western Siberian lowlands. However, current-generation models from the Global Carbon Project failed to capture the emission magnitude and trend, and may bias the estimates in future wetland CH 4 emission driven by amplified Boreal–Arctic warming and greening. Whether methane emissions from the Boreal–Arctic region are increasing under climate change is unclear, but critical for determining climate feedbacks. This study uses observations and machine learning to show an increase in wetland methane emissions over the past two decades, with inter-annual variation.