Understanding the balance between methane production and oxidation from wetlands using a minimalistic emissions model

Abstract. Wetlands play a crucial role in the global carbon cycle, both by sequestering large amounts of carbon in their soils and acting as a major natural source of atmospheric methane. Methane emissions depend strongly on soil temperature, substrate availability, and the depth of the water table relative to the soil surface, reflecting a balance between production, oxidation, and transport. Here we develop a simple mathematical model that captures how production and oxidation interact to control emissions. We condense these processes into a single ordinary differential equation, parameterised by water-table depth, soil temperature, and vegetation-derived carbon inputs, to mechanistically explore how these factors interact to control wetland methane emissions. Using emission data from six mid-latitude wetlands in the Prairie Pothole Region, we show that the model can reproduce seasonal and inter-annual variation in fluxes. Having established this agreement, we employ the model to investigate the conditions under which emissions are maximised. Peak fluxes consistently occur at or just above the soil surface and are strongly modulated by wetland-specific parameters, with oxidation acting as a significant sink in some systems. Importantly, we find that the temperature sensitivity of oxidation is a key determinant of both the magnitude and location of peak emissions. These results highlight how warming may shift emission dynamics, emphasising the need for site-specific and adaptive wetland management and restoration strategies.