Robustly detectable anthropogenic climate change signal in observed terrestrial water storage

The water cycle sustains ecosystems and societies, yet robust attribution of global changes in terrestrial water storage (TWS) to human-induced warming has been hindered by short records, large natural variability, and human water use. Here we show that a spatially coherent anthropogenic fingerprint has now emerged in satellite observations of TWS from NASA’s Gravity Recovery and Climate Experiment (GRACE). Using a formal detection and attribution framework informed by climate model simulations, we demonstrate that the observed record contains a signal that exceeds the bounds of unforced variability, strengthens in recent years, and remains robust across multiple methodological approaches. The fingerprint captures large-scale wetting and drying consistent with model projections, while divergences occur predominantly in regions strongly affected by irrigation and groundwater depletion. These findings provide the first formal evidence that climate change has left a detectable imprint on global freshwater storage, establishing TWS as a new observational indicator of human influence on the climate system and highlighting growing risks for water availability under continued warming.