South American fire activity in spring is linked to Antarctic sea ice variability

Fires in South America exert substantial social, economic, and environmental impacts, and are becoming more severe. While tropical oceanic variability is widely recognized as a key driver of fire-conducive conditions, potential influences from mid- and high-latitude oceans, especially those associated with Antarctic sea ice, remain poorly understood. Using observational analysis and numerical experiments, we find that on interannual timescales, enhanced fire activity over east-central South America is linked to increased Antarctic sea ice concentration, particularly near the Antarctic Peninsula. Increased sea ice near the Peninsula leads to anomalous synoptic eddies, which generate and maintain a positive equivalent barotropic geopotential height anomaly via eddy vorticity forcing. The resulting high pressure over South America brings hot, dry, and windy conditions that promote fire occurrence and spread. Our study suggests that the dynamics of fire activities over South America are more complex than previously thought, involving forcings as remote as Antarctic sea ice variability. An increase in sea ice concentrations near the Antarctic Peninsula can lead to hot, dry, and windy conditions over South America in spring and thus favor local fire activities, as revealed by observational records and climate model experiments.