Unveiling the impact of soil methane sink on atmospheric methane concentrations in 2020

In 2020, anthropogenic methane (CH₄) emissions decreased due to COVID-19 containment policies, but there was a substantial increase in the concentration of atmospheric CH₄. Previous research suggested that this abnormal increase was linked to higher wetland CH₄ emissions and a decrease in the atmospheric CH₄ sink. However, the impact of changes in the soil CH₄ sink remained unknown. To address this, we utilized a process-based model to quantify alterations in the soil CH₄ sink of terrestrial ecosystems between 2019 and 2020. By implementing the model with various datasets, we consistently observed an increase in the global soil CH₄ sink, reaching up to 0.35 ± 0.06 Tg in 2020 compared to 2019. This increase was primarily attributed to warmer soil temperatures in northern high latitudes. Our results emphasize the importance of considering the CH₄ sink in terrestrial ecosystems, as neglecting this component can lead to an underestimation of both emission increases and reductions in atmospheric CH₄ sink capacity. Furthermore, these findings highlight the potential role of increased soil warmth in terrestrial ecosystems in slowing the growth of CH₄ concentrations in the atmosphere.