Drought as the main climatic driver of major boreal fire seasons over the last century in eastern Canada

Abstract Projected global changes are anticipated to alter the fire regimes within boreal ecosystems. Understanding the relationship between fire activity and climate change requires a long-term dataset of annual burned area. Currently, there are only a limited number of long-term fire histories derived from detailed fieldwork. In this study, we used a spatially explicit reconstruction of forest fires from 1890 to 2024 across boreal Quebec based on historical forest maps, satellite images, and more than 3500 fire scars and 4800 establishment trees. Over the past 135 years, the fire regime has been marked by numerous minor seasons, punctuated by a few major ones, including those between 1915–1923, 1941 and, more recently, 2023. Our results indicate that severe droughts more than temperature have been the main driver of major fire seasons. Our findings indicate that a long-term record of fires provides a clearer understanding of how temperature increases, and precipitation deficits interact to influence the extent of burned areas. An increase in the intensity of climate change in the future is expected to further disturb the frequency of occurrence of major fire seasons.