In many water-stressed regions of the world, the signs are evident. Just look at the dramatically shrunk Colorado River, or the dried river bed of the Danube. Much less noticeable is the global water crisis unfolding under our feet, although it is severe.
That’s according to a recent study published in the journal Proceedings of the National Academy of Sciences. The researchers analyzed NASA satellite data to map global trends in freshwater storage at high resolution, revealing regions where human activities such as agriculture and urban water use are putting a terrible strain on groundwater supplies.
“The regions of greatest concern are those that are already recognized as water stressed, where we are now observing losses even greater than previously estimated,” said Mary Michael O’Neill, assistant researcher at the University of Maryland and NASA’s Goddard Space Flight Center, Earth.com.
Mapping a water crisis from space
Although it is natural for the Earth’s freshwater stores to fluctuate, human activity has become a dominant driver of groundwater pollution. In many parts of the world, the extraction of groundwater for irrigation, industry, and municipal use has become a fundamental part of the water cycle, and climate change is only adding to this burden.
“Estimates of global total water withdrawals range from 3,800 to 5,000 gigatons per year, and unsustainable practices have led to pervasive water scarcity,” O’Neill and her colleagues write in their report. “Identifying and accurately quantifying anthropogenic, long-term changes in freshwater resources is critical to implementing strategies to ensure water and food security.”
To this end, scientists have used data from NASA’s Gravity Recovery and Climate Experiment (GRACE) and its successor (GRACE-FO) in hundreds of studies to track changes in global freshwater supplies. These two pairs of satellites, launched in 2002 and 2018 respectively, used precise satellite-to-satellite measurements to quantify small shifts in the Earth’s gravity field that allow researchers to infer the redistribution of mass in the atmosphere, oceans and continents.
The problem is, previous methods for analyzing GRACE and GRACE-FO data could not reliably detect changes in areas smaller than about 58,000 square kilometers (150,000 square miles). To identify exactly where freshwater depletion is most severe, the researchers behind this new study applied an innovative processing method to global, non-polar terrestrial water storage data collected between April 2002 and November 2025.
This allows them to produce a terrestrial water storage trend map with five to 10 times the spatial resolution of traditional maps. The researchers then zeroed in on hotspots of freshwater pollution and used statistical models to examine how climate change and human activity are linked to these changes.
Sucking aquifers dry
The analysis revealed 40 regions where human activities are the main driver of decadal changes in terrestrial water storage. Indeed, anthropogenic land and water use was significantly associated with strong terrestrial water storage trends in every non-polar continent except Australia, and losses significantly exceeded gains.
Regions such as the Middle East and North Africa, northern India, the western United States, and southeastern Brazil were among those with widespread losses. The study shows that groundwater pumping plays a significant – and previously underestimated – role. Earlier estimates of terrestrial water storage waste associated with groundwater extraction were on average 45% lower than this new estimate, according to the researchers.
“A key conclusion of this study is that freshwater storage trends in many heavily managed basins and aquifers are more acute than previously estimated, which has implications for food and water security, hydrological and climate models, and understanding of the delicate balance of Earth system processes,” they write.
The revealing findings underscore the need for better groundwater management, especially in regions where agriculture is heavily dependent on underground water sources.