Technical note: Low meteorological influence found in 2019 Amazonia fires

Abstract. The sudden increase in Amazon fires early in the 2019 fire season made global headlines. While it has been heavily speculated that the fires were caused by deliberate human ignitions or human-induced landscape changes, there have also been suggestions that meteorological conditions could have played a role. Here, we ask two questions: were the 2019 fires in the Amazon unprecedented in the historical record?; and did the meteorological conditions contribute to the increased burning? To answer this, we take advantage of a recently developed modelling framework which optimizes a simple burnt area model, and whose outputs are described as probability densities. This allowed us to test the probability of the 2019 fire season occurring due to meteorological conditions alone. We show that the burnt area was indeed higher than previous years in regions where there is already substantial deforestation activity in the Amazon, with 11 % of the area recording the highest early season (June–August) burnt area since the start of our observational record. However, areas outside of the regions of widespread deforestation show less burnt area than the historical average, and the optimized model shows that there is a 71 % probability that this low burned area would have been expected over the entire Amazon region, including regions already witnessing deforestation and of high fire occurrence in 2019. We show that there is a