Groundwater depletion rate said doubled

WASHINGTON, Sept. 23 (UPI) -- The rate at which humans are drawing from vast underground stores of groundwater on which billions rely has doubled in recent decades, a Dutch researcher says.

Findings published in the journal Geophysical Research Letters say water is rapidly being pulled from fast-shrinking subterranean reservoirs essential to daily life and agriculture in many regions.

So much water is being drawn from below ground that its evaporation and eventual precipitation accounts for about 25 percent of the annual sea level rise across the planet, the researchers said.

Global groundwater depletion threatens potential disaster for an increasingly globalized agricultural system, Marc Bierkens of Utrecht University in Utrecht, the Netherlands, said.

"If you let the population grow by extending the irrigated areas using groundwater that is not being recharged, then you will run into a wall at a certain point in time, and you will have hunger and social unrest to go with it," Bierkens says. "That is something that you can see coming for miles."

The researchers say the rate at which global groundwater stocks are shrinking has more than doubled between 1960 and 2000, increasing the amount lost from 30 cubic miles to 68 cubic miles per year.

Because the total amount of the world's groundwater is unknown it's hard to estimate how fast the global supply would vanish at this rate, but if water was drained as rapidly from the Great Lakes they would go bone-dry in around 80 years, scientists say.