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⁻²h⁻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.

Carolina Voigt, Anna-Maria Virkkala, Gabriel Hould Gosselin, Kathryn A. Bennett, T. Andrew Black, Matteo Detto, Charles Chevrier-Dion, Georg Guggenberger, Wasi Hashmi, Lukas Kohl, Dan Kou, Charlotte Marquis, Philip Marsh, Maija E. Marushchak, Zoran Nesic, Hannu Nykänen, Taija Saarela, Leopold Sauheitl, Branden Walker, Niels Weiss, Evan J. Wilcox, Oliver Sonnentag