In a world of decreasing global water availability and increasing demand, our ability to quantify current water resources, understand the global water cycle, and predict their future trajectories is of paramount importance for water, food, and energy. Mounting pressures in a changing climate and increasing extremes are exposing a widening gap between freshwater science and the information required for effective and equitable decision-making. Now more than ever, a comprehensive, internationally coordinated, and policy-relevant synthesis of the freshwater system across scales is needed to manage water and ensure sustainable resources for human and natural systems.

This session invites contributions that focus on challenges and opportunities in global freshwater science. We highlight emerging scientific and technological advances towards a unified global synthesis of the freshwater cycle—spanning precipitation, evapotranspiration, surface water, groundwater, the cryosphere, ecosystems, human use, and water quality—to reveal patterns and test hypotheses from catchment to global scales. We encourage innovative submissions that highlight integrative approaches—including both traditional and under-utilised observations (e.g., citizen science), reanalyses, process-based models, and emerging AI-enabled inference—to advance towards an improved understanding of global freshwater at unprecedented spatial and temporal resolution, and to enable a credible, routinely updated global assessment supporting discovery and actionable solutions.