A burgeoning human population has doubled the rate at which it is pumping dry sources of groundwater in recent decades, according to a new study. Relying on a global database of groundwater use and demand, the researchers from Utrecht University calculated that the rate of withdrawal of groundwater stocks jumped from about 30 cubic miles annually (126 cubic kilometers) in 1960 to about 68 cubic miles (283 cubic kilometers) in 2000, a rate they said was clearly unsustainable.
The greatest rate of depletion occurred in some of the world’s biggest agricultural regions, including northwest India, northeastern China, and California’s central valley, according to the the study, published in Geophysical Research Letters. Marc Bierkens, a professor of hydrology and lead author of the study, warned that if over-pumping of groundwater continues “you will run into a wall at a certain point in time, and you will have hunger and social unrest to go with it.” In addition to depleting a vital resource for sustaining streams, wetlands, and ecosystems, the over-pumping of groundwater for agriculture has led to more evaporation and precipitation, with the rain eventually ending up in the oceans, accounting for about 25 percent of annual sea level rise.
