Quantifying Methane Emissions in High-Latitude North America: A Geostatistical Inverse Modeling Approach Using Multi-Source Atmospheric Measurements

Wetlands in high-latitude North America is a significant natural source of atmospheric methane (CH₄) emissions. As the second most long-lived greenhouse gas on earth, methane emissions amplify climate change effects, and rising temperatures in high-latitude wetlands may be increasing methane emissions due to the thawing of permafrost and the expansion of wetland areas. Bottom-up models of methane fluxes exhibit large uncertainties in boreal and arctic ecosystems; these models likely underestimate methane fluxes from Arctic tundra and overestimate of methane fluxes from the boreal zone in North America. The aim of the study is to quantify over a decade of methane fluxes in high-latitude North America using multiple sets of atmospheric methane observations, such as data from recent NASA aircraft campaigns as well as observations from regular tower and aircraft sites across the northern US and Canada. To compare the bottom-up methane estimates with existing tower and aircraft data products, we use a geostatistical inverse model (GIM) to estimate methane emissions across these high-latitude North America regions from years 2010 through 2022.