Global Soil Methane Uptake Estimated by Scaling up Local Measurements

Methane (CH₄) is the second most important greenhouse gas after CO₂, contributing as much as 0.5°C of warming since pre-industrial times. Soil methane uptake (SMU) is thought to be the only biological sink of atmospheric CH₄, but global SMU estimates remain highly uncertain due to challenges in scaling local data. We develop a data-driven approach to refine this global estimate by incorporating local data of 79,800 flux measurements from 198 sites. This novel approach links the global SMU budget to local SMU fluxes by varying its parameters with soil properties. Our 2003-2018 global SMU estimate is ~39.0 Tg CH₄ yr^-1 —about 30% higher than existing bottom-up estimates and consistent with top-down assessments. The projected future global SMU is shaped by temperature and atmospheric methane, though local SMU is primarily influenced by changes in soil moisture. This study emphasizes the potential of soils in climate regulation and highlights the need to focus on key biomes for better understanding the soil-atmosphere methane feedback and optimizing methane management strategies.