Forecasters say the chances of a wet El Niño winter seem less likely, dashing hopes that rain will provide relief for the parched West.

That puts more pressure on a source of water that's already deeply taxed, not only in the West, but around the world: groundwater.

Groundwater accounts for as much as a third of total water use worldwide.

For a look at the state of groundwater depletion and what that means for global water security, Take Two turns to Jay Famiglietti, senior water scientist at NASA's Jet Propulsion Laboratory.