Hidden in this millennium of data they found as many as 66 dry periods of at least three to nine years. In the entire 1,200 year period they studied, there were only three droughts that were similar in nature to the current drought.
Though none have been as severe as what California has seen in the three years since 2012. Not even the historic droughts of the late 1970s, nor the late 1980s.
The study also found that 2014 was the worst single drought year in the past 1,200 years, and that approximately 44 percent of California’s 3-year droughts have gone on to last another year, or longer.
Read more at: http://www.independent.co.uk/news/world/americas/california-drought-is-the-most-severe-in-at-least-1200-years-9908853.html