When people use freshwater beyond a physically sustainable rate, it sets off a cascade of impacts on ecosystems, people and the planet. These impacts include groundwater wells running dry, fish populations becoming stranded before they are able to spawn and protected wetland ecosystems turning into dry landscapes.

Developments in computer models and satellites have fostered a new understanding of how freshwater is being redistributed around the planet and have made clear the central role that people play in this change. This human impact is so significant that organizations like the United States Geological Survey are redrawing their water cycle diagram to include the impacts of human actions.

Equally important to understanding how people affect freshwater availability, is understanding how people and ecosystems will respond to amplified freshwater challenges including drought, water stress and groundwater depletion. While these challenges impact localized sites, their impacts are scattered across the world. To address this global water crisis, global action is urgently needed.

In our recent study, we identified the basins of the world that are most likely to be impacted by two central and interrelated aspects of water scarcity: freshwater stress, which occurs when the consumption of water surpasses renewable water supply, and freshwater storage loss, which is the depletion of freshwater in reservoirs or in groundwater bodies due to persistent overuse.