Large-Scale Climate Features Control Fire Emissions and Transport in Africa

Recent increase in extreme wildfire events has led to major health and environmental consequences across the globe. These adverse impacts underlined the need for better understanding of this phenomenon and to formulate mitigating actions. While previous research has focused on local weather drivers of wildfires, our knowledge about their large-scale climatic controls remains limited, especially in tropical Africa, which stands out as a global hotspot for fire emissions. Here, we show that interannual variability of carbon emission due to fires in the southern Congo Basin is strongly linked to low-level winds that are controlled by the Indian Ocean subtropical high. The interhemispheric transport of these emissions to West Africa relies on the intensity and position of both Indian and South Atlantic subtropical highs. Combined effects of this transport mechanism and carbon production in the source region explain a majority of the interannual variability of black carbon in West Africa. Emissions from biomass burning in different parts of the world impact air quality and climatic conditions both locally and in areas distant from the origin. Tropical Africa stands out as a hotspot of fire emissions that are primarily human-induced. In this study, we show that the year-to-year variability of the carbon emission caused by these fires in the southern Congo Basin is directly related to the local winds that are in turn controlled by conditions in the Indian Ocean. Specifically, an intensified subtropical high in the Indian Ocean leads to stronger local winds, exacerbating fire emissions in the Congo Basin. These emissions then traverse the Atlantic Ocean, affecting West Africa-an interhemispheric journey made by the atmospheric circulation patterns. Fire emissions in the Congo Basin increase when local winds are strengthened due to intensification of the Indian Ocean subtropical high Interannual variability of black carbon in West Africa is driven by fire emissions in the Congo Basin and winds over the adjacent oceans