Amazon fires in the 21st century: The year of 2020 in evidence

Abstract

AbstractAimThe aim was to evaluate fire activity for the entire Amazon and Amazon regions within each country/department from 2003 to 2020, assessing the potential contributions of drought and deforestation and contrasting 2020 with the previous years.LocationAmazoniasensu lato.Time periodAnnually from 2003 to 2020.Major taxa studiedTerrestrial plants.MethodsWe collected time series of MODIS active fire detections and burned area and assessed the yearly burned area of several land‐use/land‐cover types. We also divided the Amazon territory into 10 km × 10 km grid cells to identify annual anomalies in active fire occurrence, rainfall, maximum cumulative water deficit (MCWD) and deforestation. Rainfall and MCWD anomalies for a given cell each year consisted of annual values at least one standard deviation below average for that cell from 2003 to 2020, whereas fire and deforestation anomalies had annual values at least one standard deviation above the average for that cell.ResultsBrazil and Bolivia have contributed, on average, >70% and about 15%, respectively, of annual active fire detections in the Amazon, in addition to more than half and about one‐third of annual burned areas in the region. On average, 32% of annual burned areas in the Amazon have consisted of agricultural lands, 29% of natural grasslands and 16% of old‐growth forests. The annual extent of areas with fire anomalies was significantly associated with the annual extent of areas with deforestation anomalies, but not significantly associated with the annual extent of areas experiencing water deficit anomalies. In 2020, the total burned area in the Amazon was the greatest since 2010, and the ratio of burned area per active fire was the second greatest of the time series, despite a much lower extent of areas with anomalously high water deficit in comparison to the 2015–2016 megadrought.Main conclusionsOur findings suggest that the majority of anomalously high fire occurrences in the Amazon since 2003 did not occur in anomalous drought conditions. The intensification of agricultural fires and deforestation aggravated the burning of Amazonian ecosystems in 2020.