Enhanced extremes without intensification of South America’s water cycle from 1980 to 2010

South America hosts one of the world’s largest hydrological systems, yet terrestrial water responses to warming and human influences remain poorly constrained. Here we compare observational and model-based datasets across 95 hydrological catchments, including the Amazon and La Plata basins, to assess trends and extremes in the South American water system during 1980-2010. All datasets consistently show no continental-scale intensification (no increase) of mean precipitation, runoff, or evapotranspiration, challenging expectations of generalized terrestrial water-cycle intensification under warming. Nevertheless, the datasets show shifts in water-flux seasonality and extremes between the first and second halves of the study period. Wet-season high flows increased in the Amazon Basin and dry-season low flows declined in the La Plata Basin, indicating increasing flood and drought risks, respectively. These results highlight a regionally differentiated, complex evolution of the South American hydroclimate.