Xin Huang, Lian Xue, Aijun Ding

Wildfire in Siberia is of paramount importance in the carbon cycle and climate change as it is a major disturbance in the pan-Arctic ecosystems. In recent decades, the Siberian wildfire regime has been changing; however, less is known about the key climatic drivers and the underlying feedback over these vulnerable fire-prone landscapes. Here, based on ground-based and satellite observations and meteorological reanalysis data during the past two decades (2002–2021), we find that central Siberia features the most prominent wildfire escalation and poleward expansion. Such a shift in wildfires is closely related to drying soil moisture under a fast-warming Arctic. Our results show that a warming air temperature and weakened meridional moisture flux substantially suppress precipitation and are responsible for an increasing hydrological drought in central Siberia. We also reveal an unexpected self-amplifying feedback induced by smoke aerosol via modifying cloud microphysical properties, which further compounds wildfires in Siberia. As the Arctic warming is projected to continue, wildfires in this region are estimated to be in-tensified by 200–350% by the end of this century. This work identifies main climate drivers and feedback mechanism for the escalating wildfire risk in Siberia since the onset of this century, highlighting the importance of risk management and fire-climate adaptation in this region.