Escalating wildfires in Siberia driven by multiple climate feedbacks under a warming Arctic

Abstract

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.

Contrasting trends of carbon emission from savanna and boreal forest fires during 1999–2022

“…Such warming is consistent with in situ meteorological observations in high‐latitude regions (Dai et al, 2019; Overland & Wang, 2020), which were attributed to the changes in atmospheric circulations and local atmosphere–land interactions under global warming (Nakamura & Sato, 2022; Sato & Nakamura, 2019; Sun et al, 2021). The summer high temperature is conducive to lightning strikes (Veraverbeke et al, 2017) and tree mortality (Anderegg et al, 2013) and can drain the soil (Huang et al, 2022), which favors fire ignition and development (Richardson et al, 2022). Hence, the increase in temperature in these regions could be one cause of the local fire intensification.…”

“…Extreme BB events are repeatedly reported in recent years, for instance, those in western America in 2018 and 2020 (Brown et al, 2020; Higuera & Abatzoglou, 2021), Australia in 2019 (Boer et al, 2020), and Siberian Arctic in 2019 and 2021 (Bondur et al, 2020; Callaghan et al, 2021). These devastating fires arouse extensive concerns as some cases are found induced by local temperature increases (Huang et al, 2022; Richardson et al, 2022), which indicates a continuous aggravation of the fire severity on the globe under the ongoing global warming. More importantly, the greenhouse gases emitted from BB can add to global warming and may thereby trigger positive feedback between fire and climate change (Amiro et al, 2001).…”