the recent drought has highlighted the pressure that a changing climate puts on a snowpack-dependent water system. with the shift toward more rain rather than snow, and the earlier melting of the snowpack, water managers need to release water more frequently for flood control. this dynamic is playing out in oroville now, with the state’s water managers racing to empty water from the dam’s reservoir in advance of storms forecast to arrive wednesday. because these storms are relatively warm, they are likely to bring rain to the surrounding mountains, speeding the flow of water behind the dam.  the juxtaposition of five years of hot, dry conditions followed by more rain than reservoirs can store may seem incongruous. however, this is exactly what climate scientists have predicted for california since at least the 1980s: protracted periods of warm, dry conditions punctuated by intense wet spells, with more rain and less snow, causing both drought and floods. recent work from my lab shows that in fact this pattern is already emerging, with the conditions that create extremely warm dry years and extremely wet years both becoming more frequent.  the other bitter reality is that this extremely wet winter will not wash away the drought. depending where one looks, california lost out on one to three full years of precipitation from 2012 to 2016. that is a lot of water to make up in one year, and as of last week almost half of california was still in a state of drought. the moisture deficits that have accumulated during the drought have not been seen in our lifetimes. they have caused thousands of california residents to go without running water, resulted in groundwater contamination and permanent loss of aquifer storage capacity, and have severely stressed tens of millions of trees. as a result, even after this wet year, rural communities, groundwater aquifers and forest ecosystems will still feel the effects of the drought.  as the last five years illustrate, california’s water system is not equipped for climate change’s “new normal.” that water system must simultaneously provide for the country’s largest population and agricultural sector, and one of its most diverse natural environments. although california has greatly improved water-use efficiency in the last half-century, climate change is pushing our water system to the limit. investments in “climate smart” infrastructure can ensure the safety and security of americans in the face of climate stresses now and in the future. these investments in infrastructure upgrades and expansion would create jobs, protect communities from disasters and help prepare us for changes in the climate. this effort would have several key elements:  first, given the new climate normal in which protracted hot, dry periods are far more common, we need to deploy technologies that can increase water supply. while expensive, energy-intensive desalination options have received considerable attention, wastewater recycling technologies have improved to the point that clean, safe water can now be delivered at reduced energy cost and can even be an energy source by using the organic matter in wastewater to produce energy. investments in infrastructure to capture, store and clean urban storm water will also create new sources of water supply.
what california’s dam crisis says about the changing climate - the new york times