Spanish conquistador Hernán Cortés had recently vanquished Mexico the last time California’s snowpack was as low as it is today. The Sierra Nevada mountains, which provides the parched state with up to a third of its water supply, is at its lowest in more than 500 years, according to a paper published this month in the journal "Nature Climate Change."
To reconstruct centuries-old snow conditions, researchers analyzed data from snowpack measuring stations in the Sierra Nevada, as well as two tree-ring studies. The first study used measurements from 1,500 living and dead blue oak trees to estimate rainfall back to the year 1400. The second included tree-ring data from a different group of trees to model temperatures for the same period.
Putting all the data into a chronology, the scientists concluded that the chance a “snow drought” of this intensity would affect the entire Sierra Nevada more than once every 500 years was less than 5 percent.
California’s total precipitation in 2015 fell within the bounds of natural variability, the researchers noted, but winter temperatures were among the highest ever recorded. This lead to less snow and more rain, which the state is ill-equipped to collect and store.
And climate change could make these conditions more frequent, the researchers say.
Many Californians have pitted their hopes on promises of an imminent El Niño season to bring relief from the state’s years-long drought, researchers say that rising temperatures mean there will be much less snow and more rain.
Without a way to capture rainwater quickly, much of it will just go into the ocean, the researchers warn. Snowpack is the most important part of California’s water supply — in a normal year melting mountain snow provides the state with one-third of its water. An additional third is pumped from underground aquifers, and the remainder comes from rivers and reservoirs.
California’s drought already has taken a significant toll on the state’s water supply. To recover, around 11 trillion gallons of water — about 1.5 times the maximum volume of the largest U.S. reservoir — will be needed, according to a 2014 analysis of NASA satellite data.
With no end in sight, many California companies are embracing innovation to reduce water demands. Google, for example, is considering installing new technology such as urinal cakes containing enzymes that calcify urine so that toilets only have to be flushed a few times each day. This could save around 500,000 gallons of water a year.
The tech giant also is looking at ways to reduce water used to maintain the landscaping at its corporate campuses, including "hydrozoning" — grouping together plants with similar water needs and installing sensors to monitor irrigation use and detect leaks.
In 2013, the company saved 9 million gallons of water at its Mountain View, Calif., campus through water recycling.
Likewise, eBay has installed cooling fans among the rows of computer servers while switching to passive cooling systems, which reduces water demands for cooling. The company also employs smart irrigation systems that respond to changes in the weather.
Solar panels consume large quantities of water, largely for cleaning purposes. That’s why SunPower now uses robots to reduce the water used to clean hundreds of thousands of solar panels installed at the photovoltaic power plants it develops. Last year, the solar firm acquired Greenbotics, a company that makes Roomba-like robots that glide over solar panels at night, cleaning as they go. The system has cut water consumption at one California photovoltaic power plant by 90 percent, SunPower says.
Have you heard of any exciting water-saving innovations that could help promote drought resilience in places like California? Let us know in the comments!