Chalmers Climate Dynamics Group

In summer 2021, Siberia experienced its most extreme wildfire season on record. Yet the influence of soil moisture (SM)–atmosphere coupling on this event remains unclear. Using multisource datasets, we show that fire radiative power in the Siberian hotspot region during 2021 was nearly 9 times the 2004–2024 average (excluding 2021), representing an exceptional anomaly. Wildfire intensity scales exponentially with temperature, vapor pressure deficit, precipitation, SM, and climatic water deficit, underscoring the strong climate sensitivity of fire activity under the influence of anthropogenic climate change. Applying the flow analogue method, we found that negative SM anomalies explained more than 60% of extreme daily temperatures during peak fire days, pointing to the dominant role of surface drying in amplifying anomalous warming. During 2004–2024, SM–atmosphere coupling has strengthened and remained persistently synchronized with key fire-weather variables, driving the system toward hotter and drier states. Through SM–atmosphere coupling, the impacts of temperature and SM changes are further reinforced, potentially pushing the system beyond critical thresholds, thereby increasing the likelihood of extreme wildfires. These findings highlight the pivotal role of SM–atmosphere coupling in wildfire dynamics and its growing importance for understanding risks to high-latitude ecosystems under climate change.