Modeling Methane Emissions in an Amazonian Palm Swamp Peatland with the E3SM Land Model

Abstract:

Tropical peatlands are one of the largest natural sources of atmospheric methane (CH₄) and play a significant role in regional and global carbon budgets. It is expected that biogeochemical and hydrometeorological dynamics play important roles affecting CH4 emissions from Amazonian peatlands, especially during the warmer and wetter climate, but these key processes are still limited in most current Earth system models. Here, we present simulations of methane processes in an Amazonian palm swamp peatland (Iquitos, Peru) for the period 1990–2019 using the E3SM land model (ELM), which is incorporated with a new microbial-functional-group-based CH₄ module. To quantify the model performance in simulating carbon cycling, we evaluated the model output against observational fluxes of carbon dioxide (CO₂) and CH₄ (2018-2019) and other field data. A parameter sensitivity analysis was further performed to determine the key factors controlling the CH₄ processes using a Latin hypercube sampling approach. Initial tests of ELM at the site scale found the model is able to simulate Amazonian peatland CH₄ processes in a more mechanistic way. CH₄ production and consumption were sensitive to microbial activities, plant ecophysiology, and hydrometeorological drivers. This study will enable future simulations of the broader palm swamp peatlands in the Amazonian region to assess the historical and future spatiotemporal patterns of CH₄ emissions.