Coherent changes in global high and low flows

• Changes in global natural streamflow changes are estimated in 1982–2018. • Wetting, drying, diverging and equalizing regions cover ∼49.3 %, ∼31.8 %, ∼6.2 % and ∼12.6 % of global land, respectively. • 58.3% regions of precipitation changes are consistent with streamflow change patterns during 1982–2018. Streamflow shifts threaten water security under climate change. While gauged basins have been extensively studied, ungauged regions remain poorly characterized. Using high- and low-flow trends from 2,213 unregulated catchments, we predict four types of streamflow changes globally. From 1982 to 2018, 81.1% of studied regions exhibited coherent trends: 49.3% showed wetting (increased high and low flows), and 31.8% showed drying (decreased flows). The remaining areas experienced diverging (6.2%) or equalizing (12.6%) changes. Wetting dominated arid, snow, and polar climate regions, whereas drying prevailed in equatorial and temperate zones. Streamflow trends aligned with precipitation changes in 58.3% of areas, while 39.6% were also driven by non-precipitation factors, highlighting complex hydroclimatic interactions. Ongoing shifts demand enhanced water management and hazard adaptation.