Recent Drought in California—Anomaly or Regular Episode

In 2013-2014, media outlets dedicated significant attention to the drought in California. Granted, dollar figures on the agricultural output from California are placing the state at the top amongst agricultural states. California produces 80% of the world's almonds, and at $4.347 billion value in 2012, it is the third top agricultural commodity of the state. The demand for almonds in the past 4-5 years has increased the price 2 to 3 times.

Soaring price is good news for producers, but it takes about a gallon of water to grow a single almond. Thus, with $42.6 billion agricultural output at stake, the attention to the drought in California is understandable. Is the recent drought really an exceptional event, or this is one of the regular anomalies that happen every so often?

Using NASA precipitation data from climate reanalysis of the past 35 years, and satellite observations from the past 17 years, we show that this is both. The current deficit in precipitation has been lasting two years, and similar dry events have been regularly appearing in recent decades in California. However, unlike the past events that seem to had always recovered to the climatological normal, the current episode shows anomalously persistent deficit with few signs of recovery.

The reanalysis and observational precipitation data manifest with high confidence that El Niño, the warm phase of the El Niño Southern Oscillation (ENSO), may help to recoup the deficit in precipitation. Signs of developing El Niño appeared in the spring of 2014. Unfortunately, at present it seems to be a weak ENSO event, and it appeared too late into the 2013-2014 rain season. It is highly unlikely that California will recover its water deficit before the end of 2014. What's more, unless the current El Niño strengthens, the 2014-2015 will very likely be the third deficit water year in a row.