Underestimation of Methane Emissions From the Sudd Wetland: Unraveling the Impact of Wetland Extent Dynamics

Tropical wetlands account for ∼20% of the global total methane (CH₄) emissions, but uncertainties remain in emission estimation due to the inaccurate representation of wetland spatiotemporal variations. Based on the latest satellite observational inundation data, we constructed a model to map the long-term time series of wetland extents over the Sudd floodplain, which has recently been identified as an important source of wetland CH₄ emissions. Our analysis reveals an annual, total wetland extent of 5.73 ± 2.05 × 10⁴ km²  for 2003–2022, with a notable accelerated expansion rate of 1.19 × 10⁴ km² yr⁻¹ during 2019–2022 driven by anomalous upstream precipitation patterns. We found that current wetland products generally report smaller wetland areas, resulting in a systematic underestimation of wetland CH₄ emissions from the Sudd wetland. Our study highlights the pivotal role of comprehensively characterizing the seasonal and interannual dynamics of wetland extent to accurately estimate CH₄ emissions from tropical floodplains.