Land use and climatic drivers of early 21st-century fire activity in the Amazon

Abstract

Fire plays a critical role in shaping the Amazon’s ecosystem and carbon dynamics, yet the relative contributions of climatic and land-use drivers remain debated. Here, we used 0.5° by 0.5° aggregated satellite-based active fire (AF) data (2002–2020) combined with land-cover change and climate reanalysis datasets to (1) quantify spatiotemporal change of fire patterns, (2) evaluate the interrelationships between drought, deforestation, and fires while comparing the relative contributions of climatic and land-use drivers, and (3) assess the impact of policy interventions on fire incidence. Our findings reveal that, despite a declining trend in overall fire detections, fire activity has shifted from regional concentration to broader dispersion, advancing deeper into the forest interior. While drought anomalies account for approximately 30 % of fire variability, spatial regression analysis highlights the dominant role of deforestation (coefficient=0.67) and farmland expansion (coefficient=0.20), compared to drought (coefficient=0.05). Notably, deforestation’s contribution to positive fire anomalies declined from ∼ 69 % (Phase I: 2004–2008) to ∼ 41 % (Phase IV: 2016–2020) of the Action Plan for the Prevention and Control of Deforestation in the Legal Amazon (PPCDAm), reflecting the partial effectiveness of conservation policies in mitigating fire risk. Nevertheless, the persistent interaction among fires, deforestation, and farmland expansion underscores the critical role of human activities in creating ignition-prone landscapes and stimulating fire occurrences. This study demonstrates the compounding effects of climate and land-use changes on Amazonian fire dynamics, and emphasizes the urgent need for integrated land use policies and climate adaptation strategies to address the enduring fire pressures and safeguard the Amazon’s carbon stocks and biodiversity.