Quantifying the contributions of atmospheric circulation and land–atmosphere coupling to the rapid increase in fire weather risk over Eastern Siberia

Wildfires in Eastern Siberia have intensified rapidly in recent decades, with increasing impacts on air quality and Earth’s climate. This intensification is closely linked to rising fire weather risk, as indicated by vapor pressure deficit (VPD), which is jointly modulated by large-scale circulation and land–atmosphere coupling, yet their respective contributions remain poorly quantified. Here we attribute the 2004–2024 summer VPD trend over Eastern Siberia using the circulation and soil moisture analogue methods. Observations show a pronounced VPD increase of 0.67 hPa decade⁻¹, which is primarily associated with variations in atmospheric circulation that contribute 0.41 hPa decade⁻¹, while the soil-moisture-related land contribution reaches 0.38 hPa decade⁻¹. These two contributions are not independent, reflecting a coupled pathway of circulation-induced land feedbacks, estimated at ~0.20 hPa decade⁻¹. CMIP6 simulations further confirm the robustness of this mechanism, showing that land–atmosphere coupling amplifies the circulation-driven VPD trend. The dominant circulation anomalies are associated with warm sea surface temperature (SST) anomalies over the Barents Sea, which excite a Rossby wave train across high-latitude Eurasia and favor subsidence, suppressed precipitation, and reduced near-surface relative humidity, thereby elevating VPD. Circulation-induced soil drying, likely related to precipitation suppression, further enhances atmospheric dryness by altering surface energy partitioning and increasing net radiation. Together, these results show that recent fire-weather risk intensification in Eastern Siberia is primarily controlled by atmospheric circulation, with substantial amplification by circulation-triggered land–atmosphere feedbacks.