Subpolar North Atlantic decadal cooling may have aggravated recent Eastern Siberian wildfires

Recent wildfire outbreaks in Eastern Siberia herald far-reaching impacts on air quality and carbon balance. While anthropogenic warming is identified as the primary driver of increased wildfire risk, the role of internal climate variability remains unclear. Here, we perform an attribution analysis to reveal the impact of internal climate variability on the recent escalation of wildfires, using causal inference, path analysis, and large ensemble simulations. Our results show that the soaring wildfires in Eastern Siberia from 2001 to 2021 were mainly induced by a decline in fire-season precipitation of 16 mm decade^-1, which accounts for approximately 42% of the observed increase in burned area. This declining precipitation was likely partially associated with concurrent unforced subpolar North Atlantic decadal cooling, which excited a Rossby wave train throughout high-latitude Eurasia, generating an anticyclonic circulation anomaly over Eastern Siberia. Our findings highlight the potential for internal climate variability to impact future wildfire risk.