Increasing Fire Activity in African Tropical Forests Is Associated With Deforestation and Climate Change.

Fires were historically rare in tropical forests of West and Central Africa, where dense vegetation, rapid decomposition, and high moisture limit available fuels. However, increasing heat and drought combined with forest degradation and fragmentation are making these areas more susceptible to wildfires. We evaluated historical patterns of Moderate Resolution Imaging Spectroradiometer active fires in African tropical forests from 2003 to 2021. Trends were mostly positive, particularly in the northeastern and southern Congo Basin, and were concentrated in areas with high deforestation. Year‐to‐year variation of fires was synchronized with increasing temperature and vapor pressure deficit. There was anomalously high fire activity across the region during the 2015–2016 El Niño. These results contrast with the drier African woodlands and savannas, where fire has been decreasing. Further attention to fires in African tropical forests is needed to understand their global impacts on carbon dynamics and their local implications for biodiversity and human livelihoods. Plain Language Summary: Fires have historically been rare in the moist tropical forests of West and Central Africa. However, these forests are becoming more vulnerable to fire because climate change is causing higher temperatures and drought stress in the tropics. Human activities such as agriculture, logging, and mining also fragment the remaining forests and make them more susceptible to fire. We used measurements of actively burning fires from Earth observing satellites to study how the amount of fire in African tropical forests has changed from 2003 to 2021. There were several areas with strong trends of increasing fire, mainly in the Congo Basin. In contrast, there were almost no locations where fire was decreasing. The increasing fire trends occurred in locations where deforestation was occurring and climate was becoming warmer and drier. During 2015–2016 global weather patterns caused by an exceptionally strong El Niño event were associated with higher‐than‐normal fire activity throughout the tropical forests in West and Central Africa. Increasing fire is a concern because it can release greenhouse gasses into the atmosphere, reduce the amount of carbon stored in the African tropics, degrade habitats for species that live in tropical forests, and decrease the amounts of wood, food, medicine and other resources that forests provide for humans. Key Points: Active fire detections increased from 2003 to 2021 across Central Africa, with positive fire trends concentrated in the Congo BasinFire increased in areas with high deforestation and the trends were synchronized with increasing temperature and vapor pressure deficitThere was higher‐than‐usual fire activity in tropical African forests associated with the exceptionally strong 2015–2016 El Niño event [ABSTRACT FROM AUTHOR]