California in a Warming World

The problem with climate change is change. It’s a simple thing, really, but it’s a point sometimes missed. It’s not that it gets warmer or colder or wetter or drier. It’s that it gets different, and the societal systems we’ve put in place to cope with what used to be “normal” become less useful.

A case in point: California. I just ran across this paper from the October Journal of the American Water Resources Association. It’s from a group at UC Davis that ran global 12 climate change scenarios against California water supply models to see what happens as things warm up. As you might expect, the snow melts sooner:

Even most scenarios with increased precipitation result in less available water because of the current storage systems’ inability to catch increased winter streamflow in compensation for reduced summer runoff.

Available water supplies decrease in 9 of the 12 scenarios they looked at. It’s worth noting, too, that in a number of scenarios the Davis team looked at, the decrease in available supply as a result of warming is comparable to the increase in demand from growing population in California. In other words, vulnerability as a result of climate change is comparable in this analysis to vulnerability as a result of societal change.

That’s “Estimated Impacts of Climate Warming on California Water Availability Under Twelve Future Climate Scenarios,” Tingju Zhu, Marion W. Jenkins, and Jay R. Lund, JAWRA, Oct. 2005.


  1. “In other words, vulnerability as a result of climate change is comparable in this analysis to vulnerability as a result of societal change.” Lucky us, we’ll get to double our pleasure!

    Just to clarify one aspect of this, the problem with our current infrastructure is that it is designed to catch the snow-melt only after the direct flood hazard from the winter rains (see today’s news!) has passed. Full dams don’t work very well for flood control. My suspicion is that the solution to this won’t be building a lot more (very expensive) dams, but will emphasize buying water rights from agriculture (with the result that a whole lot of land will be taken out of production). The synergy comes in when one realizes that the land thus made available for other purposes will be that deemed most suitable for continued sprawl. 🙂

  2. Steve –

    On agricultural water use, one of the interesting bits to me in this is the authors’ suggestion that agricultural water use will drop significantly by 2020 as urban use rises, implying that the ag->urban water transfer is either explicitly or implicitly built into the demand side of their model

  3. CA is finding, John and Steve, that the market will pay for urban water uses – that is: the subsidized ag water can be resold at market rates and urban/industrial users will pay more for offstream water. The IID/CO compact/San Diego/Westlands WD is a perfect case in point. Ag can’t compete at these prices, so farmers are selling their water.

    Secondly, offstream uses may be curtailed for environmental reasons (related to drinking water, which really is an environmental reason) because of recent findings in the Delta:

    Lastly, this will be esp. problematic as the timing of ag HOH deliveries will be affected as well, with fewer summer crops due to less snowpack, unless IID/others buy CO river HOH. Cotton, dairy, other San Joaquin crops will be affected, with ripple effects throughout the economy.

    IMHO, these outcomes will result in much higher food prices as soon as p*ssed off legislators (if they actually govern any more) stop the taxpayer-subsidized transfers. Caveat: I no longer live in CA and don’t follow the water wars closely down there, so they may have stopped these transfers, but they haven’t legislated to avert climate change.



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