Water Woes: Dramatic Increase of Droughts in California Is a Bellwether of Future Climate Impacts

, former director, California & Western States | January 22, 2014, 3:31 pm EDT
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It’s now well known that California is facing an unprecedented drought emergency. Governor Brown declared a state of emergency to address the drought last week, and in his annual State of the State message today indicated that the situation we face may be a harbinger of things to come due to climate change. Our California climate scientist Dr. Juliet Christian-Smith shares her thoughts below on what this really means and the kinds of measures the state needs to be exploring to truly address this problem:

“The state of California has formally declared a drought emergency due to a lack of winter rainfall and water reserves at only 20 percent of normal levels. With 2013 the driest year in recorded history in California and no significant rainfall in the forecast, Governor Jerry Brown recently described the state’s current condition as “a mega-drought.” The current bone-dry weather should be seen as a bellwether of what is to come in California, with increasing periods of drought expected with climate change.

Looking at the historic record of dry and critically dry conditions since 1906, it is clear that the risk of drought has markedly increased in California in the 21st century (see infographic below). In fact, California has seen about a 30 percent increase in the frequency of droughts since 2000 as compared to a 1906-1999 baseline. Put another way, Californians have spent almost half of the 21st century in drought.


As the governor himself stated, drought declarations will not make it rain. Drought declarations and other crisis-driven responses often do little to provide real solutions. In fact, many of the short-term actions taken by the state during drought years, such as groundwater mining, actually leave us more vulnerable to more frequent or severe droughts in the future.

Now is the time for California to more effectively manage its water supplies, designing approaches that work under a wider range of climate conditions than in the past. Instead, excessively dry conditions often lead to renewed calls for infrastructure projects, like the twin tunnels (formerly known as the “peripheral canal”) that have been proposed for decades, rebranded as responses to climate change.

While there is certainly a need for improved water infrastructure in some areas of the state, the governor’s drought declaration suspends California Environmental Quality Act review “on the basis that strict compliance [with CEQA review] will prevent, hinder, or delay the mitigation of the effects of the emergency.” This is seen by many as an attempt to get large, water infrastructure projects approved without having to ask important questions about California’s new climate reality. Questions like: even if we build new reservoirs or tunnels, will there be enough water to operate them efficiently? And who will pay for projects that are not able to deliver water in dry years, when we are the most vulnerable? A 2011 World Bank report recognized that “long-lifespan infrastructure…is generally less adaptable to changes whereas short-lifespan infrastructure can be replaced in the long term as the climate changes.” Indeed, there are a variety of smaller scale solutions that are generally much less expensive, energy-intensive, and environmentally damaging than large-scale water infrastructure projects that are not easily adapted to changing climate conditions, including water use reduction, reuse, recycling, and restoration.

Our current water polices are not sustainable. California needs to adopt climate-resilient water management solutions that address a range of climate conditions and help assure more reliability, especially in dry years. The state should start with the following:

  • Better groundwater management: Groundwater mining has left ample below-ground water storage capacity that can store water in a larger range of climate conditions.
  • Urban water conservation: The average Californian uses almost double the amount of water used by the average South Australian per day, and much of this use is outdoors or “discretionary” (not necessary to human health and well-being).
  • More efficient agricultural water uses: While urban water users are already required to use 20 percent less by 2020, there are no statewide targets for agricultural water users.
  • Saving energy: Using water efficiently saves energy; the State Water Project is the single largest electricity consumer in the state. The California Energy Commission has concluded that water efficiency is, in many cases, the fastest and cheapest methods to conserve energy and reduce the climate change emissions associated with energy use.

In his State of the State address today, Governor Brown talked about the need not just to address the drought we are experiencing now, but to prepare for the future:

“We do not know how much our current problem derives from the build-up of heat-trapping gasses, but we can take this drought as a stark warning of things to come. The United Nations Panel on Climate Change says – with 95 percent confidence – that human beings are changing our climate. This means more droughts and more extreme weather events, and, in California, more forest fires and less snow pack.”

With increasing demand and drought straining our water resources, we need to adopt policies that address both the causes and impacts of climate change.

Correction: January 23, 2014
California has seen about a 30 percent increase in the frequency of droughts since 2000 as compared to a 1906-1999 baseline, not 39 percent as first published.


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  • Steve Bloom

    Hi Juliet, thanks for your reply.

    I won’t have a chance to look carefully at the linked data until later, but note that it’s very much *not* statewide; i.e it’s just for central valley runoff (and not drought as such). Absent an historical statewide drought index (doesn’t exist as far as I know), statewide precipitation still seems closer to statewide drought.

    That aside, the basic problem with the graph showing a single 14-yr period remains, i.e. that it doesn’t actually prove the claim and is potentially misleading as to the situation. Would a 14-yr running average of central valley runoff even show the most recent 14 years to be exceptional, especially relative to the 1920s? That’s not at all obvious from eyeballing the numbers you linked, but as I said I’ll have a more careful look later.

    • Juliet Christian-Smith

      Hi Steve,
      To your point about comparing a 14 year period (which is all we have thus far for the 21st century), we ran a statistical analysis comparing two equal time periods: 1906-1959 and 1960-2013.
      Using the Fisher test, the two time periods are significantly different at a 90% confidence interval with the frequency of droughts being higher for the latter time period.

      • Steve Bloom

        Hi Juliet, thanks again for your attention to this.

        Was that analysis also done using the central valley runoff figures? In any case, it isn’t reflected in the graphic or the post. And stat sig, sure, but to what degree (and to what degree of drought beyond the threshold definition; sounds like you may not have differentiated) and what does that prove about the very recent trend?

        Another issue re the graphic is the claim that 2013 is the driest year on record. That’s the case for precipitation, but *not* for the runoff data you linked (since calendar year runoff largely reflects the prior winter); 2008 e.g. is lower.

        I’ll say again that I think there’s a great, effective analysis to be done of all this. The one above just isn’t it.

  • Juliet Christian-Smith

    Dear Steve,
    Thanks for your fact checking, though it looks like we are comparing apples and oranges as we are looking at two different data sets that provide different measures of drought. Here, we are examining the California Department of Water Resources’ Water Year Hydrologic Classification Indices (available online at http://cdec.water.ca.gov/cgi-progs/iodir/wsihist).
    Drought years are considered those water years classified as either “dry” or “critical.” Importantly, these classifications are based on runoff, not precipitation. Thus, we are analyzing the change in the likelihood of hydrological droughts – while the precipitation data you posted could be analyzed to consider changes in meteorological droughts. There is a good summary of the different ways of measuring drought on the University of Nebraska’s webpage here: http://water.unl.edu/web/drought/typesofdrought.

  • Steve Bloom

    “Looking at the historic record of dry and critically dry conditions since 1906, it is clear that the risk of drought has markedly increased in California in the 21st century (see infographic below).”

    Except the 11-yr mean trend shows no such thing: http://www.wrcc.dri.edu/monitor/cal-mon/TIMESERIES/TIMESERIES_PCP_CY_STATEWIDE.png. 14-yr would be little different. What the complete record does show is that 2013 is an amazing outlier. A very strong case for concern can be made based on that (haven’t seen anyone do the analysis, but is this a 3-sigma event?), taking into account climate projections along with observed trends in snowpack and (IIRC) soil moisture.

    An organization with “scientists” in the name and employing same must be extra-careful with this sort of thing. Please amend this statement appropriately.