[B-CG04] Methane in terrestrial and aquatic ecosystems: from microbes to the atmosphere

[BCG04-P01] Seasonality of temperature sensitivity of methane emissions from natural wetlands

*Jinshuai Li^1,2, Tianxiang Hao¹, Meng Yang^1,2, Guirui Yu^1,2, Zhi Chen^1,2 (1.Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China, 2.College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China)

Keywords:natural wetlands, methane, temperature sensitivity, seasonality

Temperature sensitivity is one of the most important parameters for estimating methane emissions from natural wetlands, but our understanding of temperature sensitivity is still not clear enough. Methane emissions from natural wetlands are determined by production and oxidation processes, which are mainly co-regulated by redox conditions and substrate supply. Redox conditions are mainly regulated by water level, while substrate supply is mainly related to ecosystem productivity. However, the seasonal characteristics of water level and ecosystem productivity lead to seasonal differences in wetland methane production and oxidation mechanisms. Therefore, we hypothesized that there is also seasonality in the temperature sensitivity of wetland methane emissions. Here, we validate the seasonality of the temperature sensitivity of methane emissions from natural wetlands using the FLUXNET-CH₄ dataset. We first divided the year into six seasons based on temperature data, and then quantified the temperature sensitivity of different seasons separately. Then, we quantified the main influencing factors of temperature sensitivity. Finally, we quantified the global wetland methane emission rate based on seasonal temperature sensitivity. The results showed that the methane emission temperature sensitivity showed a trend of increasing and then decreasing with seasonal changes. The temperature sensitivities of methane emissions from wetlands with different vegetation types and water level conditions also followed this feature. The temperature sensitivity in early summer was the highest, with an apparent activation energy of 0.60; the temperature sensitivity in late winter was the lowest, with an apparent activation energy close to zero. Air temperature, soil temperature, water table, ecosystem productivity and respiration explained 85% of the variability in temperature sensitivity. Simulation results based on CMIP6 climate scenarios showed that future wetland methane emission hotspots are mainly concentrated in tropical and subtropical regions. Our results emphasize the seasonal differences in temperature sensitivity, which will help to further improve the model simulation accuracy in the future.