Abstract Unprecedented warming of Arctic–boreal regions (ABR) has poorly understood consequences on carbon cycle processes. Limited winter data add uncertainty to annual methane (CH4) budgets. In this study, winter CH4 flux measurements were conducted using the snowpack diffusion gradient method over five ABR ecosystem types in Canada and Finland: closed–crown and open–crown coniferous boreal forest, boreal wetland, erect–shrub and prostrate–shrub tundra. Boreal forest uplands acted as net CH4 sinks with soil liquid water content identified as an important environmental control, while the boreal wetland acted as net CH4 source during winter. We identified several wetland tundra CH4 emission hotspots and large spatial variability in boreal wetland CH4 emissions. Snow cover conditions and near‐surface soil temperature did not impact significantly CH4 exchanges. Our results indicate non–negligible winter CH4 flux, which must be accounted for in annual carbon balance and terrestrial biosphere models over ABR.
Observations from the Little Bunker
Last updated: November 30, 2025 04:25 AM
Atmospheric CO₂
426.8 ppm
+18.1
ppm/year
Atmospheric CH₄
1927.61 ppb
+2.73
ppb/year
Global Temperature
+1.48 °C
Peak: +1.73°C
World Population
8.1 billion
+67
million/year