Rapid increase of climate extremes across northern Amazonia

Amazonia’s exceptional biodiversity, cultural significance, and ecosystem services make it pivotal to global and regional sustainability. However, the region is increasingly threatened by climate extremes, which exacerbate the effects of land use change (Barlow et al., 2018) and bring about abrupt changes in social and ecological condition (Bennett et al., 2023; Berenguer et al., 2021; Campanharo et al., 2022; Lapola et al., 2023; Libonati et al., 2022; Lima et al., 2024; Machado-Silva et al., 2020; Tadano et al., 2024). Yet, while climate extremes are increasing in many parts of the world (Huntingford et al., 2024), we lack a high-resolution Amazon-wide assessment that compares if they differ from climate averages or identifies spatial hotspots where rates of change are highest. Here we address this by assessing Amazonia’s changing climate at high spatial resolution within seasons and across the year, considering both central trends (50th percentile) and trends of extremes (5th and 95th percentiles). Our analysis includes a new measure of water deficit that accounts for the effects of temperature on evapotranspiration. High temperature extremes and temperature-linked measures of water deficit are both changing at a much faster rate than central trends, and their rates of change are greatest in the driest period. While the central trend of mean temperature change across Amazonia (0.21°C per decade, dec-1) is comparable to the global average, the upper extreme of maximum temperatures in the driest period increased by 0.50°C dec-1. These Amazon-wide trends also mask considerable spatial variation. Crucially, we identify a new region of high climate risk in central-north Amazonia, where over 700,000 square kilometres have experienced increases in extreme dry season temperatures of at least 0.77 °C dec-1 (i.e., ≥3.31 ºC over 43 years). Adaptation measures are urgently required to address the impacts of these rapid changes in climate extremes, including preventing the key stressors of deforestation, forest fires and other disturbances that amplify climate risks.