By Tom Randall
10 April 2015
(Bloomberg) – The California heat of the past 12 months is like nothing ever seen in records going back to 1895. The 12 months before that were similarly without precedent. And the 12 months before that? A freakishly hot year, too.
What's happening in California right now is shattering modern temperature measurements—as well as tree-ring records that stretch back more than 1,000 years. It's no longer just a record-hot month or a record-hot year that California faces. It's a stack of broken records leading to the worst drought that's ever beset the Golden State.
The chart below shows average temperatures for the 12 months through March 31, for each year going back to 1895. The orange line shows the trend rising roughly 0.2 degrees Fahrenheit per decade, just a bit faster than the warming trend observed worldwide.
The last 12 months were a full 4.5 degrees Fahrenheit (2.5 Celsius) above the 20th century average. Doesn't sound like much? When measuring average temperatures, day and night, over extended periods of time, it's extraordinary. On a planetary scale, just 2.2 degrees Fahrenheit is what separates the hottest year ever recorded (2014) from the coldest (1911).
California's drought has already withered pastures and forced farmers to uproot orchards and fallow farmland. It's costing the state billions each year that it goes on. Governor Jerry Brown issued an executive order this month for the first mandatory statewide water restrictions in U.S. history, with $10,000-a-day penalties against water agencies that fail to reduce water use by 25 percent. [more]