A South Atlantic atmospheric river dipole as a key precursor of Amazon wildfires

Wildfires in the Amazon have far-reaching climatic and ecological impacts, yet their predictability remains limited. Here we identify a large-scale atmospheric precursor of August–September Amazon wildfires: a June–July dipole mode of South Atlantic atmospheric rivers (ARs), characterized by suppressed AR activity in the north and enhanced activity in the south. This dipole is strongly linked to interannual variability in Amazon wildfire activity through land–atmosphere feedbacks associated with reduced precipitation and humidity, enhanced surface warming and solar radiation, and increased vegetation stress. We estimate that wildfire-related forest loss associated with this AR dipole mode accounts for approximately 26% of the observed interannual variability in total forest loss. Adding the South Atlantic AR dipole to predictors based on May–June sea surface temperature anomalies and June–July wildfire activity yields substantial predictive skill for August–September burned area (R² = 0.67). Climate model projections further indicate a future intensification of the South Atlantic AR dipole mode, implying increased wildfire-driven ecological degradation in the Amazon under continued warming. This study identifies a South Atlantic atmospheric river dipole as an early warning signal for Amazon wildfires, linking shifts in moisture transport to hotter, drier conditions and increased fire activity in the region.