Fire plays an important role in shaping terrestrial ecosystem and atmospheric composition, affecting surface-level air quality as well as Earth’s climate. On one hand, the trend and magnitude of fire activity over the last few centuries are controversial, which hinders understanding of preindustrial to present-day aerosol radiative forcing. On the other hand, ongoing climate change will lead to warmer and drier conditions in certain areas, with a consequent increase in the number and size of fires, yet large uncertainties exist in these projections. Fires pose critical challenges in both the present and the coming decades. The goal of this session is to solicit recent studies that advance our understanding and interpretation of the historical and future trends of fire activity as well as their consequences on air quality, climate, and health.