Abstract: Wildfires significantly affect vegetation, soil thermal and hydrological as well as carbon dynamics. This study uses a process-based biogeochemistry modeling framework that is incorporated with land surface energy balance, soil thermal and hydrological dynamics and their effects on carbon and nitrogen cycling to simulate these dynamics and carbon budget in northern high latitudes. Here we present our model results on North American boreal forests from 1986 to 2020 using satellite-derived burn severity data. We find that fires remove ecosystem carbon through combustion emissions and reduce net ecosystem production, making the ecosystem lose 3.5 Pg C during 1986-2020 and changing the boreal forests from a carbon sink to a source in the region. Our modeling also suggests that fire-impacted canopy influences surface energy balance, inducing significant summer soil temperature changes, affecting nitrogen mineralization rate and plant nitrogen uptake, thereby changing plant net primary productivity; the altered soil temperature also affects soil carbon decomposition. As a result, the canopy effects on surface energy balance significantly affect boreal forest ecosystem carbon sink and source activities in the region. Currently we are examining the wildfire impacts on permafrost dynamics and hydrological cycle as well as carbon and nitrogen dynamics in northern Eurasia.