Methane (CH₄) accounts for up to 25% of atmospheric warming to date, but large uncertainty exists in methane emissions estimates from wetlands (the largest natural CH₄ source) using biogeochemistry models. This uncertainty arises largely because wetland CH₄ dynamics depend on a diverse array of poorly-represented physical, biological and chemical processes, as well as a large number of poorly-constrained uncertain parameters to characterize these processes. This project will examine the sensitivity of CH₄ emissions to a large set of parameters and optimize the most sensitive parameters, at observation sites covering a wide range of soil types, vegetation types and climatic conditions. The main goals are to provide insights into key parameters that drive uncertainty in wetland CH₄ emissions at each site and parameter transferability between sites; enhance the process-level understanding of mechanisms and controls underlying CH₄ biogeochemistry; and enable more reliable projections of the magnitude and variability of global and regional wetland CH₄ emissions under a changing climate.