2026 Session 5: Past and future change in global river flows

Rivers play a central role in the global water cycle, yet their flow regimes are increasingly shaped by human-driven climate and land-use changes. This contribution synthesizes current knowledge on historical and anticipated shifts in river discharge, with emphasis on annual runoff totals, seasonal flow patterns and abrupt hydrological changes. Observational records reveal clear but regionally varied trends, including rising flows at high latitudes and declining flows across many mid latitude and subtropical basins. Snow influenced regions, in particular, display notable alterations in the timing of seasonal discharge. These observed patterns are broadly consistent with climate model simulations, indicating an emerging anthropogenic influence on river behaviour, though attribution remains complicated by interactions among greenhouse gas forcing, vegetation responses, land use changes and water management practices. Looking forward, model projections point to continued divergence in hydrological futures, with some regions expected to become wetter and others drier, alongside intensifying shifts in seasonal dynamics. Despite significant advances in monitoring and modelling, substantial uncertainty remains regarding the combined effects of climate change and direct human alterations of terrestrial systems. Addressing these gaps will require improved global observation networks, methodological progress in attribution, and integrated approaches to support sustainable water management, ecosystem resilience and climate adaptation strategies. Duration: 36:23 min Speaker: Lukas Gudmundsson (ETH-Zurich, Switzerland) Related links/publications: https://www.nature.com/articles/s4301...