The Methanotrophy Model (MeMo v1.0) is a process-based model to simulate methane uptake by soil bacteria at global and local scales [1]. It was validated against direct observational data, demonstrating lower errors compared to previous existing models and employed in the latest global methane budget [2]. MeMo has two key components: gas diffusion into the soil and a biological module of consumption. In particular, the biological component involves a base oxidation rate constant at 0º (k0) which is influenced by moisture, temperature (parametrized as a Q10 function) and nitrogen. These parameterizations are based on a thorough review of previous studies, however, there is a lack of available k0 values and Q10 values for comparison, which are susceptible to vary across ecosystems and latitudes. This model was structured with a single Q10 value for the entire globe and three different values of k0 for three ecosystems (an improvement of previous models, but still a large structural limitation). Thus, investigating the impact of temperature on oxidation rate through Q10 and the variation of k0 across different ecosystems is crucial for improving the modeling of global methane uptake by soils and the subsequent estimations.

The central issue to be addressed in this work, is the estimation of Q10 and k0 values for methane oxidation by soil bacteria in the laboratory, utilizing samples from various ecosystems. This has not been addressed previously because it was only when we parameterized modern models that we realized this key gap of information [1]. These data are crucial for enhancing global models aimed at estimating methane uptake by this specific sink.

The key goals of the study include: 1) Synthesizing available information on Q10 and k0 values for methanotrophy. 2) Measuring both values in the laboratory using soil samples from diverse ecosystems and 3) refine MeMo V1, to include the new values as well as higher- resolution driving datasets.

Success can be assessed by examining the global implementation of the model, incorporating distinct Q10 and k0 values for different ecosystems worldwide. In particular, a metric for success will be a reduction in model global errors (RSME, Bias, R2) when comparing updated results with available observations. This approach aims to provide a more accurate representation of methane uptake by soils on a global scale.

The measurement of Q10 and k0 values from different ecosystem types and their implementation in a global model would:

• Improve our understanding of how temperature affects this microbial process, from local to the global scale
• Provide key values of the base oxidation rate (k0) across different ecosystems
• The implementation of the updated values in the MeMo model will result in more accurate estimations of global methane uptake by soils and the potential to generate local, ecosystem and regional estimates
• This will also help identify strategic regions that may present an increase or reduction in methane uptake at the face of climate change (e.g. permafrost, drylands)
• In addition, these updates will modify the current global methane budget, by improving the computation of global uptake by soils
• Finally, I hope my results will generate strategies and recommendations to enhance the methane uptake by soils