Intact Amazon forests hit a record low gross primary productivity level in 2023-2024

Abstract In the Amazon, the dry season of 2023 as well as the beginning of the wet season in 2024 were marked by unprecedented high temperatures and large precipitation deficits. While the tropical forests in the Amazon play a crucial role in the global carbon cycle and are a biodiversity hotspot, they were also shown to suffer from El-Niño related droughts in the past, leading to legitimate concerns about the ecological consequences of the recent climate conditions. To this day, the tools that we have in hand to determine those ecological consequences have lagged behind the present due to the complexity to acquire and process new remote sensing data or run land surface models. In this study, we employed advanced machine learning models trained on state-of-the-art remote sensing and dynamic global vegetation model estimates of gross primary productivity (GPP). The models provide near real-time GPP estimates, revealing significant productivity reductions during the 2023/2024 drought, unmatched in at least the past 30 years. Negative GPP anomalies were more widespread across the Amazon than during any other recent major drought event. The Climate-GPP relationships that emerged from the models suggest that future temperature increases and changes in precipitation will severely challenge Amazon forest resilience.