Increasing aerosol emissions from boreal biomass burning exacerbate Arctic warming

The Northern Hemisphere boreal region is undergoing rapid warming, leading to an upsurge in biomass burning. Previous studies have primarily focused on greenhouse gas emissions from these fires, whereas the associated biomass burning aerosols (BBAs) have received less attention. Here we use satellite-constrained modelling to assess the radiative effect of aerosols from boreal fires on the climate in the Arctic region. We find a substantial increase in boreal BBA emissions associated with warming over the past two decades, causing pronounced positive radiative effects during Arctic summer mostly due to increased solar absorption. At a global warming level of 1 °C above current temperatures, boreal BBA emissions are projected to increase 6-fold, further warming the Arctic and potentially negating the benefits of ambitious anthropogenic black carbon mitigation. Given the high sensitivity of boreal and Arctic fires to climate change, our results underscore the increasingly relevant role of BBAs in Arctic climate. Boreal fires are expected to increase with warming, but how the aerosols emitted in these fires affect the climate is not well understood. Here the authors show that this increase in boreal fire aerosols results in a positive radiative forcing, leading to additional Arctic warming.