Groundwater Crisis

An article in Nature Climate Change describes the growing depletion of aquifers worldwide. Exceeding the rate of replenishment, in some cases due to drought, threatens agricultural production.

The ongoing California drought is evident in these maps of dry season (Sept–Nov) total water storage anomalies (in millimeter equivalent water height; anomalies with respect to 2005–2010). California’s Sacramento and San Joaquin river basins have lost roughly 15 km3 of total water per year since 2011 — more water than all 38 million Californians use for domestic and municipal supplies annually — over half of which is due to groundwater pumping in the Central Valley.

Changes in groundwater mass are tracked by NASA's GRACE satellite.

Update (June 28, 2016):  A study from Stanford shows nearly three times as much ground water in California's Central Valley than previously estimated. But it may be threatened with contamination from oil and gas drilling.