Pantanal wetland wildfires are associated with drought in interconnected biomes

Pantanal is the largest tropical wetland in the world and has been extremely affected by these wildfires recently, such as in 2020 and 2024. The largest rivers that supply the Pantanal originate in the Brazilian highlands (“plateau”), so the availability of surface water in the biome (“plain”) is strongly associated with the hydrological dynamics and land use and cover of surrounding biomes such as the Amazon, Cerrado, and Atlantic Forest. Although the hydrological connections between these biomes and the local factors contributing to wildfires have been well explored, there appears to be a lack of comprehensive studies at a macro-scale that demonstrate the associations between historical above-average fires in the Pantanal and the climatic and biospheric conditions of its hydrologically interconnected biomes. Therefore, this study aimed to analyze a 32-year historical series (1989–2020) of burned areas in the Pantanal and identify the drivers of above-average wildfires. We explored local environmental variables as well as those of surrounding biomes. We found that 13 out of 32 analyzed years stand out for a total burned area above normal, and only 1999 showed a larger burned area than 2020. The results of this study demonstrate that water dynamics from soil to atmosphere, such as decreased soil moisture, vegetation moisture and evapotranspiration, and increased drought, including during previous years, in the Pantanal and the surrounding forested biomes (Amazon and Atlantic Forest) are associated with the occurrence of above-average wildfires in the Pantanal wetland. In addition, the 32-year trend analysis revealed that widespread drought has increased in the Pantanal and all analyzed interconnected biomes, indicating that the world’s largest tropical wetland will likely see more above-average wildfires. Our results have implications for macro-scale adaptive management, integrated watershed management, fire risk early detection, and the preparedness of teams responsible for combating fires in the Pantanal.