The banality of California’s ‘1,200-year’ drought

The south fork of Lake Oroville, California's second largest reservoir, in September 2014. Photo by Kelly M. Grow/California Department of Water Resources.

The south fork of Lake Oroville, California’s second largest reservoir, in September 2014. Photo by Kelly M. Grow/California Department of Water Resources

By Jay Lund

California’s ongoing drought will continue to break records and grab headlines, but it is unlikely to be especially rare from a water policy and management perspective.

Estimates of the current drought’s rarity range from once in 15 years to once in 1,200 years (Griffin and Anchukaitis 2014), depending on the region and indicators used (precipitation, stream runoff, soil moisture or snowpack). In the Middle Ages, large parts of California had droughts far worse than this one, some lasting more than a century (Stine 1994). The probability of California experiencing a once in 1,200-year drought during a short human lifetime is extremely low.

The chance that this dry period is a “new normal” is probably small. Many parts of Australia are paying for expensive desalination plants built when a severe drought was misinterpreted as a new normal. If this drought is as unusual as once in 1,200 years, then why pay heed beyond just getting through it? We are unlikely to see the likes of it again.

The obsession over El Niño and the California drought masks the reality that the atmospheric condition is poorly correlated with stream flows in Northern California, where 75 percent of the state’s water supply originates.

East Coast news media should keep this perspective: Every summer California has a drought far drier and longer than the eastern U.S. has ever seen. This explains California’s extensive water and irrigation infrastructure (and why people move to California).

Distressed vineyard in Coachella Valley on July 10th 2014.

Drought-stressed vineyard in Coachella Valley in July 2014. Photo by Kelly M. Grow/California Department of Water Resources

The uniqueness of an individual drought is fascinating. Each drought is unique in area, persistence, dryness, temperature, internal pattern and how it ends. California’s current drought is unusually severe, and certainly the worst since 1988-1992. Groundwater in the Tulare basin is probably lower than at any time in human history. This drought also has been unusually warm, leading to it having the lowest snowpack in 500 years and driest soil in 1,200 years. In precipitation and flows on major rivers, the 2012-2015 drought so far ranks between the third and eighth driest years on record.

By focusing on unique aspects of a drought, any drought can become an incredibly rare event. Becoming engrossed in the superlatives, however, can distract from the business of managing water shortages and preparing longer-term solutions.

What’s more relevant for water policy and management is the banality of drought. We should expect to see droughts in California of severity similar to the current drought about once or twice in a generation. Given climate change and the growth in expectations and values for diverse water uses, it seems reasonable to expect such droughts a bit more frequently than in the past. The warmer temperatures in this drought seem likely to become normal for future droughts, with disproportionate effects on ecosystems and small streams.

Lake Oroville's Bidwell Marina in September 2014. Photo by Kelly M. Grow/California Department of Water Resources

Lake Oroville’s Bidwell Marina in September 2014. Photo by Kelly M. Grow/California Department of Water Resources

Agencies, cities, bankers, insurers, farmers and residents should prepare for greater regularity of droughts as harsh as the current one. Severe drought in California should be reclassified from a rare “act of God” to something more like a business cycle swing that recurs several times in a lifetime or career.

California is managing pretty well under the current drought in most areas (Howitt et al. 2015; Hanak et al, 2015) and can survive much more severe and prolonged droughts, if managed well (Harou et al, 2010).

It is more important to focus on managing the dry event and preparing for future ones than understanding the fascinating intricacies of drought origins and statistics. But we probably will continue to obsess about drought statistics and El Niño anyway.

Further reading

Belmecheri S, Babst F, Wahl ER, Stahle DW and Trouet V. (2015). “Multi-century evaluation of Sierra Nevada snowpack.” Nature Climate Change. doi.org/10.1038/nclimate2809

Cayan D and Mount J. “Don’t count on El Niño to end the drought.” Viewpoints/The PPIC Blog. July 9, 2015

Griffin D and Anchukaitis KJ. (2014), “How unusual is the 2012–2014 California drought?Geophys. Res. Lett., 41, 9017–9023, doi:10.1002/2014GL062433

Hanak E, Mount J, Chappelle C, Lund J, Medellín-Azuara J, Moyle P and Seavy N. What If California’s Drought Continues? 20 pp. PPIC Water Policy Center, San Francisco, CA, August 2015

Harou JJ, Medellin-Azuara J, Zhu T, Tanaka SK, Lund J, Stine S, Olivares MA and Jenkins MA. (2010).  “Economic consequences of optimized water management for a prolonged, severe drought in California.” Water Resources Research, doi:10.1029/2008WR007681, Vol. 46

Howitt R, MacEwan J, Medellín-Azuara J, Lund J. “Drought bites harder, but agriculture remains robustCaliforniaWaterBlog. Aug. 18, 2015

Howitt R, Medellín-Azuara J, MacEwan D, Lund J and Sumner D. (2015). “Economic Analysis of the 2015 Drought for California Agriculture.” Center for Watershed Sciences, UC Davis. 16 pp. August 2015

Lund J. (2014). “Could California weather a mega-drought?CaliforniaWaterBlog. June 29, 2014

Lund J and Mount J. “Will California’s drought extend into 2015?California WaterBlog. June 15, 2014

Schonher T and Nicholson SE. (1989). “The Relationship between California Rainfall and ENSO Events.” Journal of Climate, Vol. 2, Nov. pp. 1258-1269

Stine S. (1994). “Extreme and persistent drought in California and Patagonia during medieval time“. Nature, 369, 546–549, doi:10.1038/369546a0

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9 Responses to The banality of California’s ‘1,200-year’ drought

  1. gymnosperm says:

    Reblogged this on geosciencebigpicture and commented:
    Terrific post. Couldn’t agree more. California drought? What else is new?

    Like

  2. tsac0008 says:

    The expansion of agricultural land and water use that has occurred since the 1979 drought was ill advised. With the doubling of the state’s population and the incumbent immigration to the Central Valley it was more than predictable that domestic wells that had already been contaminated by corporate agriculture would then be depleted as well. California has reached natural limitations that its greed can no longer accommodate. The earth is sinking around the largest terra forming event that has occurred on this planet. Ultimately crops and groundwater water use will have to be adjudicated in the southern Central Valley and that will only be successful by disallowing continued expansion of the populace and construction that comes with that population increase. Hard times are ahead for California.

    Like

  3. Robert Pyke says:

    I agree with gymnosperm. An excellent post that puts things in perspective. At best the third worst drought in the last one hundred years. This is not the end of the earth, it is just normal climate variability. But, as demand for water in California has increased and hardened we need to get a bit smarter about dealing with this variability.

    Like

  4. Rich Persoff says:

    The current “drought” — e.g., lack of rainfall — may not be especially unusual statistically, so Dr. Lund’s description of it as “banal” isn’t too far off. BUT our over-mining this resource has greatly increased the intensity of the dislocations suffered because of an insufficiency of available water.
    We see those affected putting great pressure on the government to spend public money — e.g., MY taxes — to rescue them from their unsustainable choices. Let those who hoped to profit take some responsibility for the adverse personal results of our own actions. Or is that too Socialistic?

    Like

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