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International audience; Tropical wetlands are estimated to represent about 50 % of the natural wetland methane (CH 4) emissions and explain a large fraction of the observed CH 4 variability on timescales ranging from glacial–interglacial cycles to the currently observed year-to-year variability. Despite their importance , however, tropical wetlands are poorly represented in global models aiming to predict global CH 4 emissions. This publication documents a first step in the development of a process-based model of CH 4 emissions from tropical flood-plains for global applications. For this purpose, the LPX-Bern Dynamic Global Vegetation Model (LPX hereafter) was slightly modified to represent floodplain hydrology, vegetation and associated CH 4 emissions. The extent of tropical floodplains was prescribed using output from the spatially explicit hydrology model PCR-GLOBWB. We introduced new plant functional types (PFTs) that explicitly represent floodplain vegetation. The PFT parameterizations were evaluated against available remote-sensing data sets (GLC2000 land cover and MODIS Net Primary Productivity). Simulated CH 4 flux densities were evaluated against field observations and regional flux inventories. Simulated CH 4 emissions at Amazon Basin scale were compared to model simulations performed in the WETCHIMP intercomparison project. We found that LPX reproduces the average magnitude of observed net CH 4 flux densities for the Amazon Basin. However , the model does not reproduce the variability between sites or between years within a site. Unfortunately, site information is too limited to attest or disprove some model features. At the Amazon Basin scale, our results underline the large uncertainty in the magnitude of wetland CH 4 emissions. Sensitivity analyses gave insights into the main drivers of floodplain CH 4 emission and their associated uncertainties. In particular, uncertainties in floodplain extent (i.e., difference between GLC2000 and PCR-GLOBWB output) modulate the simulated emissions by a factor of about 2. Our best estimates, using PCR-GLOBWB in combination with GLC2000, lead to simulated Amazon-integrated emissions of 44.4 ± 4.8 Tg yr −1. Additionally, the LPX emissions are highly sensitive to vegetation distribution. Two simulations with the same mean PFT cover, but different spatial distributions of grasslands within the basin, modulated emissions by about 20 %. Correcting the LPX-simulated NPP using MODIS reduces the Amazon emissions by 11.3 %. Finally, due to an intrinsic limitation of LPX to account for season-ality in floodplain extent, the model failed to reproduce the full dynamics in CH 4 emissions but we proposed solutions to this issue. The interannual variability (IAV) of the emissions increases by 90 % if the IAV in floodplain extent is accounted Published by Copernicus Publications on behalf of the European Geosciences Union. 1520 B. Ringeval et al.: Methane emissions from floodplains in the Amazon Basin for, but still remains lower than in most of the WETCHIMP models. While our model includes more mechanisms specific to tropical floodplains, we were unable to reduce the uncertainty in the magnitude of wetland CH 4 emissions of the Amazon Basin. Our results helped identify and prioritize directions towards more accurate estimates of tropical CH 4 emissions, and they stress the need for more research to constrain floodplain CH 4 emissions and their temporal variability , even before including other fundamental mechanisms such as floating macrophytes or lateral water fluxes.