Integrated Climate Radiative Forcing from Arctic-Boreal Fires

Fire is a major disturbance mechanism in arctic-boreal ecosystems and results in warming and cooling feedbacks to the climate system. Greenhouse gas emissions from fires are a major positive feedback, yet post-fire carbon sequestration in recovering ecosystems partly offsets this. In addition, fire removes part of the organic soil layer and may result in permafrost thaw and consequent greenhouse gas emissions. Yet, fire-induced changes in ecosystem structures result in a larger spring-time snow cover compared to unburned areas, and this imposes a negative climate feedback through increased surface albedo. These various climate forcings are spatially and temporally heterogeneous and depend on various landscape components and fire regime characteristics. Understanding the net climate forcing effect is crucial in managing and mitigating climate change impacts on carbon cycling. We applied the concept of radiative forcing in a quantitative spatial assessment of the net climate feedbacks induced by arctic-boreal North American fires. We capitalize upon the state-of-the-art carbon combustion estimates by the Arctic Boreal Vulnerability Experiment Fire Emissions Database (ABoVE-FED) and a novel climate forcing framework to predict fire-driven changes in net forcing under historical and future climate scenarios. In our analyses we incorporated all fires between 2001 and 2019, evaluating the net fire-induced forcing over the regrowth successional phase (at 20-years after fire) and after full succession (at 80-years after fire). Our results highlight the spatial and temporal heterogeneity in climate forcings from arctic-boreal fires, and in future work we plan to characterize spatiotemporal patterns of the net climate feedback.