Quantifying Arctic-boreal methane emissions using atmospheric observations and a global inverse model

The Arctic-Boreal region is vulnerable to rapid climate change. Thawing of the permafrost and extended warm periods are expected to turn the region into a hotspot of enhanced CH₄ emissions. We estimated CH₄ fluxes by assimilating atmospheric CH₄ mixing ratio data from a regional network into a global atmospheric inverse model, resulting in a mean uncertainty reduction of ~68% across the domain and improved agreement with observations. From 2010 to 2021, the Arctic-Boreal region emitted 45.4 ± 0.7 TgCH₄ y^-1 ( ~ 7% of global emissions), with no significant overall trend. However, on the regional scale a positive trend emerged in the Western Siberia Lowlands. Arctic-Boreal wetland emissions increased during warmer years, suggesting possible future increases as warming continues. Emissions varied regionally, with western Russia showing higher fluxes. Changes in winter hydroclimate significantly influenced emissions in the Western Siberian Lowlands, likely by enhancing the availability of soil moisture through snowmelt in spring. Our findings emphasize the importance of accounting for both temperature effects and changes in wetness, when assessing Arctic CH₄ future emissions.