Arctic soil methane sink increases with drier conditions and higher ecosystem respiration

Arctic wetlands are known methane (CH₄) emitters but recent studies suggest that the Arctic CH₄ sink strength may be underestimated. Here we explore the capacity of well-drained Arctic soils to consume atmospheric CH₄ using >40,000 hourly flux observations and spatially distributed flux measurements from 4 sites and 14 surface types. While consumption of atmospheric CH₄ occurred at all sites at rates of 0.092 ± 0.011 mgCH₄ m^-2 h^-1 (mean ± s.e.), CH₄ uptake displayed distinct diel and seasonal patterns reflecting ecosystem respiration. Combining in situ flux data with laboratory investigations and a machine learning approach, we find biotic drivers to be highly important. Soil moisture outweighed temperature as an abiotic control and higher CH₄ uptake was linked to increased availability of labile carbon. Our findings imply that soil drying and enhanced nutrient supply will promote CH₄ uptake by Arctic soils, providing a negative feedback to global climate change.