Smoke-Weather Interaction Affects Extreme Wildfires and Air Pollution Exposure in Diverse Coastal Regions

Wildfire that threatens lives and infrastructure, deteriorate air quality and damages ecosystem services has become a growing problem in the Anthropocene. The interdecadal variability of wildfire intensity has long been attributed to climate change, however, an increasingly frequent extreme wildfires with devastating impact highlight our limited insight on large fire-related feedbacks over the short term. Here we show the primacy of synoptic-scale feedbacks in driving extreme fires in both Mediterranean and monsoon regions via accelerating wind speed, drying air and suppressing rainfall. Furthermore, the radiative effects of smoke aerosols tend to substantially stabilize temperature stratification and trap the pollutants near the surface, thereby elevating fine particle concentration by over 300 µg/m³ and forming severe smoke pollution. Such a fire-weather interaction forms a positive feedback loop and contributes to an excess air-pollution exposure of more than 40% in extreme events over densely populated region like western United States and southeastern Asia. Our study underscores the urgency of understanding fundamental mechanisms of fire-weather interaction within our planet’s climate system, which might be an overlooked driver but could better support large fire mitigation.