[Ed. – Meaning (a) it’s happened before, and (b) it happened long before carbon dioxide emissions began to soar in the mid-20th century.]
[A]ccording to a new scientific study, this drought is the worst that California has experienced in 1200 years. Researchers studying tree rings concluded that “the current event is the most severe drought in the last 1200 years, with single year (2014) and accumulated moisture deficits worse than any previous continuous span of dry years.”
The study, published as a research letter in the journal of the American Geophysical Union, was written by Daniel Griffin of the University of Minnesota and Kevin J Anchukaitis of the Woods Hole Oceanographic Institution. By measuring tree rings from nearly 300 blue oaks, and comparing those measurements with data from older trees such as giant sequoias, scientists were able to generate estimates of rainfall for centuries. …
“Although there are 37 times over the past 1,200 years when there were three-year dry periods in California, no period had as little rainfall and as hot of temperatures as 2012-14, the scientists concluded,” the Mercury News reported.