Vox: Some of the world's most important farming regions rely on freshwater from large underground aquifers that have filled up slowly over thousands of years. Think of the Central Valley aquifer system in California. Or the Indus basin in Pakistan and India. This groundwater is particularly valuable when rain is scarce or during droughts.
But that groundwater may not last forever. Data from NASA's Grace satellites suggests that 13 of the world's 37 biggest aquifers are being seriously depleted by irrigation...