Human footprint drives sustained evapotranspiration decline in Amazonia

Evapotranspiration (ET) in the Amazon strongly couples land and atmosphere to regulate water, carbon, and energy. However, deforestation and fires diminish the function of deep-rooted trees, weakening the forest’s water recycling. Shifts in dry season dynamics further alter ET timing and magnitude. Here we use high-resolution, data-constrained hydrological modeling to separate the effects of anthropogenic disturbances and droughts on ET and vegetation function across the Amazon and adjacent biomes from 2003 to 2020. We show that ET declines from deforestation persist 38% longer than those from fire, and 29% longer than from drought alone. When the three disturbances combine, ET losses increase by 22% and persist 72% longer compared to individual stressors. Assessing the response across neighboring biomes, we find that grasslands and savannas in the Cerrado are most vulnerable to droughts, with ET recovery often taking over seven or more years, while wetlands in the Pantanal recover rapidly due to sustained moisture availability. Vegetation productivity declined in regions with compounding stresses, despite concurrent greening trends. Our findings reveal that repeated human-driven stresses weaken ecosystem resilience, threatening long-term ecological stability. Isolating the human fingerprint on ET trajectories is pivotal to guide sustainable land-use transitions that preserve biosphere–atmosphere coupling in South America’s tropical systems.