Boreal-Arctic wetland methane emissions under arctic warming and greening (Invited)

Wetland CH4 emissions represent ~20-30% of global CH4 emissions and the CH4 emissions exacerbate the warming climate because the radiative power of CH4 is ~30 times stronger than CO2 over a 100-year time horizon. Furthermore, wetland CH4 over the Boreal-Arctic region are vulnerable to climate warming, yet understanding of their long-term dynamics remains uncertain. The ongoing synthesis efforts at FLUXNET-CH4 sites provide useful data to parameterize Bottom-up (BU) models. Existing BU modeling studies have shown some progress in capturing the observed CH4 emissions at a handful of FLUXNET-CH4 sites after careful calibration. However, BU models still suffer from large parametric uncertainty and use incomplete biogeochemical theories. In this work, we strive to better understand boreal-arctic wetland CH4 emissions through: 1) directly infer long-term CH4 emissions using eddy covariance and chambers observations; 2) calibrating BU models (GCP-CH4 models) with machine learning and FLUXNET-CH4 site observations.