Assessment of Burned Areas during the Pantanal Fire Crisis in 2020 Using Sentinel-2 Images

The Pantanal biome-a tropical wetland area-has been suffering a prolonged drought that started in 2019 and peaked in 2020. This favored the occurrence of natural disasters and led to the 2020 Pantanal fire crisis. The purpose of this work was to map the burned area's extent during this crisis in the Brazilian portion of the Pantanal biome using Sentinel-2 MSI images. The classification of the burned areas was performed using a machine learning algorithm (Random Forest) in the Google Earth Engine platform. Input variables in the algorithm were the percentiles 10, 25, 50, 75, and 90 of monthly (July to December) mosaics of the shade fraction, NDVI, and NBR images derived from Sentinel-2 MSI images. The results showed an overall accuracy of 95.9% and an estimate of 44,998 km(2) burned in the Brazilian portion of the Pantanal, which resulted in severe ecosystem destruction and biodiversity loss in this biome. The burned area estimated in this work was higher than those estimated by the MCD64A1 (35,837 km(2)), Fire_cci (36,017 km(2)), GABAM (14,307 km(2)), and MapBiomas Fogo (23,372 km(2)) burned area products, which presented lower accuracies. These differences can be explained by the distinct datasets and methods used to obtain those estimates. The proposed approach based on Sentinel-2 images can potentially refine the burned area's estimation at a regional scale and, consequently, improve the estimate of trace gases and aerosols associated with biomass burning, where global biomass burning inventories are widely known for having biases at a regional scale. Our study brings to light the necessity of developing approaches that aim to improve data and theory about the impacts of fire in regions critically sensitive to climate change, such as the Pantanal, in order to improve Earth systems models that forecast wetland-atmosphere interactions, and the role of these fires on current and future climate change over these regions.

Automated summary

The Pantanal biome in Brazil has been experiencing a prolonged drought since 2019, leading to natural disasters and the 2020 Pantanal fire crisis. This study used Sentinel-2 MSI images to map the extent of the burned area in the Brazilian portion of the Pantanal during the crisis. A machine learning algorithm (Random Forest) was used to classify the burned areas, resulting in an overall accuracy of 95.9% and an estimate of 44,998 km(2) burned. This research highlights the importance of developing improved approaches to understanding the impacts of fire in climate change-sensitive regions like the Pantanal.