Seasonality of temperature dependence of methane fluxes from natural wetlands

Temperature dependence is a crucial parameter in estimating methane (CH 4 ) fluxes from natural wetlands, yet our understanding of this parameter remains inadequate. Seasonal fluctuations in water levels and ecosystem productivity lead to seasonal differences in CH 4 production and oxidation. We hypothesized the existence of seasonality in the temperature dependence of CH 4 fluxes. To validate this hypothesis, we analysed the FLUXNET‐CH4 dataset to determine the seasonal variation in temperature dependence of CH 4 fluxes. We divided the year into six seasons based on air temperature and assessed the temperature dependence for each season using the apparent activation energy calculated by the Boltzmann–Arrhenius equation. Our results showed that temperature dependence showed a unimodal trend with seasons, with the apparent activation energy peaking in early summer (0.60 eV) and reaching its lowest point in late winter (−0.02 eV). This seasonal pattern of temperature dependence was consistent across wetlands with different vegetation types and hydrological conditions. Modelling of global wetland CH 4 emissions based on seasonal temperature dependences showed a 19% (4%–45%) increase in emission rates under the most severe temperature rise scenario. Our results emphasize the seasonality of temperature dependence, which will help to further improve current and future predictions of wetland CH 4 emissions. Read the free Plain Language Summary for this article on the Journal blog.