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

• Published in: Nature climate change Vol. 13; no. 10; pp. 1095 - 1104
• Main Authors: Voigt, Carolina, Virkkala, Anna-Maria, Hould Gosselin, Gabriel, Bennett, Kathryn A., Black, T. Andrew, Detto, Matteo, Chevrier-Dion, Charles, Guggenberger, Georg, Hashmi, Wasi, Kohl, Lukas, Kou, Dan, Marquis, Charlotte, Marsh, Philip, Marushchak, Maija E., Nesic, Zoran, Nykänen, Hannu, Saarela, Taija, Sauheitl, Leopold, Walker, Branden, Weiss, Niels, Wilcox, Evan J., Sonnentag, Oliver
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.10.2023; Nature Publishing Group
• Subjects: 704/106/125; 704/106/47; 704/106/694; 704/47; Aquatic ecosystems; Arctic climate changes; Arctic soils; Atmospheric methane; Availability; Carbon; Climate Change; Climate Change/Climate Change Impacts; Earth and Environmental Science; Emitters; Environment; Environmental Law/Policy/Ecojustice; Fluctuations; Global climate; Machine learning; Methane; Negative feedback; Nutrient cycles; Respiration; Seasonal variations; Soil; Soil drying; Soil moisture; Soil temperature; Uptake; Wetlands; Arctic region; Climate change; Cryospheric science; Biogeochemistry
• ISSN: 1758-678X; 1758-6798
• DOI: 10.1038/s41558-023-01785-3

Arctic wetlands are known methane (CH 4 ) emitters but recent studies suggest that the Arctic CH 4 sink strength may be underestimated. Here we explore the capacity of well-drained Arctic soils to consume atmospheric CH 4 using >40,000 hourly flux observations and spatially distributed flux measurements from 4 sites and 14 surface types. While consumption of atmospheric CH 4 occurred at all sites at rates of 0.092 ± 0.011 mgCH 4  m −2  h −1 (mean ± s.e.), CH 4 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 CH 4 uptake was linked to increased availability of labile carbon. Our findings imply that soil drying and enhanced nutrient supply will promote CH 4 uptake by Arctic soils, providing a negative feedback to global climate change. The Arctic is estimated to be a source of atmospheric methane but the sink capacity may be underestimated. This study shows that methane uptake in well-drained Arctic soils is driven by soil moisture and carbon availability, indicating a potential increased methane sink under climate change.