Unprecedented social-ecological impacts of the 2023 extreme drought in the central Amazon.

While the 2023 record-breaking drought led to widespread social-ecological impacts across Amazonia, local impacts of such extreme events are rarely described in detail. Here we leverage a large interdisciplinary data collection related to social and ecological impacts in the Central Amazon. Compound hazards (reduced river water levels, lack of rainfall, high water/air temperatures, river erosion and fire smoke) led to major impacts, including an unprecedented mortality of 209 river dolphins and blooms of the potentially ichthyotoxic Euglena sanguinea phytoplankton. Fish kills in lakes and changes in caiman relative abundance along floodplain channels were observed, as well as lower-than-usual production of flowers and fruits in floodplain trees. Impaired river transportation was the main socio-economic impact, affecting important value chains such as the arapaima fisheries and manioc flour production, as well as access to healthcare, drinking water and urban markets. Our results also show the contrasting impacts between rural and urban populations, with the latter presenting a higher resilience throughout the event. Continuous records of impacts like those presented here are fundamental to guide future disaster management policies in Amazonia. This is particularly important to help vulnerable remote people and ecosystems during extreme hydro-climatic events, which are likely to increase in the near future.