How climate variability modes influenced the fires in South America during the extreme droughts of 2023-2024

In 2023 and 2024, tropical South America experienced unprecedented, record-breaking droughts and anomalous surface air temperatures, which severely affected fire risk, biodiversity, and socioeconomic activities. Notably, 2024 witnessed an 85% increase in burned area in the Brazilian Amazon compared to 2023. In this context, a deeper understanding of fire responses to climate variability has become a critical research focus. Using regression analyses, this study investigates the influence of sea surface temperature anomalies in the Pacific, Atlantic, and Indian Oceans on rainfall variability and fire occurrence in the Amazon and Brazilian Cerrado regions during the dry seasons of 2023 and 2024. The results indicate that in 2023, the combined effect of El Niño, the tropical North Atlantic (TNA) warming and a positive Indian Ocean Dipole (IOD) intensified and prolonged drought conditions, significantly increasing fire activity into October and November in the northern and central Amazon. In 2024, simultaneous TNA and Indian Ocean Basin-Wide (IOBW) warming were the primary drivers of the drought, with peak fire activity occurring from June to September in the southwestern Amazon, including Bolivia, Paraguay, and central Brazil. Findings indicate that interactions among multiple climate variability modes not only intensify droughts but also alter the temporal and spatial distribution of fires, thereby impacting areas that have historically been less affected. These findings underscore the importance of accounting for climate variability when developing effective public policies for fire prevention and control in the region.