It's important to note that California's drought, while extreme, is not an uncommon occurrence for the state. In fact, multi-year droughts appear regularly in the state's climate record, and it's a safe bet that a similar event will happen again. Thus, preparedness is key," said Richard Seager, report lead author and professor with Columbia University's Lamont Doherty Earth Observatory.According to the report (embedded below), the drought was caused by
- Weather conditions were key to explaining the event - a high pressure ridge off the West Coast diverted the track of storms during all three winters, typical of historical droughts.
- West Coast high pressure was rendered more likely during 2011-14 by effects of sea surface temperature patterns over the world oceans.
- The drought's first year (2011/2012) was likely the most predictable, when La Nina effects largely explained high pressure off the West Coast, though simulations indicate that high pressure continued to be favored due to ocean effects in 2012-14.
Model simulations indicate that human-induced climate change increases California precipitation in mid-winter, with a low-pressure circulation anomaly over the North Pacific, opposite to conditions of the last 3 winters. The same model simulations indicate a decrease in spring precipitation over California. However, precipitation deficits observed during the past three years are an order of magnitude greater than the model simulated changes related to human-induced forcing. Nonetheless, record setting high temperature that accompanied this recent drought was likely made more extreme due to human-induced global warming.As to the temperatures, perhaps they missed it but the satellite data as of December 2014 it has been 18 years and two months since the earth warmed.
The full NOAA report follows: