California’s drought has not spared A. G. Kawamura.
A former state secretary of food and agriculture, Mr. Kawamura grows vegetables and strawberries south of Los Angeles in Orange County. He was relatively lucky, losing 15 percent of one green bean crop when his well went dry last June, two and a half weeks before harvest.
Still, the fields have remained fallow since then. “If I didn’t have another farm, I would be out of business.”
Despite his worry over California’s four-year drought and its weirdly warming winter, Mr. Kawamura remains optimistic about farmers’ ability to adapt through human ingenuity. Irrigation systems have evolved from furrows to sprinklers to drips in the three generations since his family began farming in what is now the highly urbanized Los Angeles basin.
These days, he said, there’s a water district experimenting with human waste, extracting methane and hydrogen to use for fuel and injecting the water into the aquifer. Australians have developed a technique to irrigate with brackish water, using the brine as fertilizer and cleaning out the water for use on site. He also sees promise in techniques to harvest water from the air.
Innovation, however, has a limit.
California’s main challenge is not technological, but economic and political. One thing to keep in mind is that the state still has . It just doesn’t have enough for every possible use, no matter how inefficient and wasteful.
California’s cities consume , on average. That’s 40 percent more than the per capita and more than double that of in Australia.
A byzantine system of historic rights established to allocate water across the American Southwest actually Even today, as almond trees in the Central Valley’s Kern County stand dead, farmers elsewhere in the state are with this extremely thirsty crop, which as Los Angeles does in three.
And the decision by Gov. Jerry Brown to on water use, even though they consume some 80 percent of the surface water used in the state, underscores the scale of the political challenge.
But even if California moves to a more efficient system for allocating water among competing users — a big if — its problems are just beginning.
Most scientists agree there is little evidence to conclusively tie the recent instances of extreme weather to human-driven . But there is little question that will have a big impact on the weather and the availability of water, in the not-so-distant future.
A new from Stanford University concluded that human emissions of carbon dioxide had increased the odds that California will suffer repeated combinations of warm temperature and low precipitation, “the co-occurring warm-dry conditions that have created the acute human and ecosystem impacts associated with the ‘exceptional’ 2012—2014 drought in California.”
And if such emissions continue growing throughout the century, researchers from the NASA Goddard Institute for Space Studies, the Lamont-Doherty Earth Observatory at Columbia University and Cornell University estimated that the entire American Southwest would face at least an 80 percent chance of suffering from 2050 through 2099.
In a nutshell, climate change is expected to increase rain or snowfall in areas that are already relatively wet and reduce it in areas that are already relatively dry, like the Southwest, Mexico and Australia. Dry areas, moreover, will be warmer, increasing loss of water through evaporation and transpiration.
“Climate change will steadily and fundamentally lower the baseline for water availability in the West,” said Benjamin Cook, a co-author of the study affiliated with the Goddard Institute and Columbia’s observatory.
And what water California gets will arrive the wrong way. According to one study by researchers from several California institutions, even if average annual precipitation were to remain relatively unchanged,
The state relies on a water cycle that has remained roughly stable for decades: Heavy snow falling in the Sierra in the winter accumulates as snowpack, holding water until it is needed in the dry summer. The state built a sophisticated conveyance and storage infrastructure based on these patterns.
They are unlikely to hold in the future. Snowpack in the Sierra is at only 5 percent of its historical average. Less precipitation is falling as snow, and snow is melting five to 30 days earlier than in the last half-century. The risk is that water will fill reservoirs too soon, perhaps overflowing or evaporating early, leaving too little water available for the most critical months.
Last week the so-called of business and political leaders pushing for action against climate change issued its , laying out an array of challenges from extremely hot days that would reduce productivity in agriculture and construction, to flooding that could swamp much of Silicon Valley.
Even if carbon emissions were to peak before midcentury, calculations by Mr. Cook and his colleagues suggest that the Southwest will still face an exceptionally high risk of suffering a mega-drought of a scale not seen since the “Medieval Warm Period” parched the region from about 1100 to 1300.
Some researchers say that period caused the end , driving its people out of their stone cities perched high on the cliffs in the Four Corners region of the Southwest. “Our results point to a remarkably drier future that falls far outside the contemporary experience of natural and human systems in Western North America,” wrote the researchers. That “may present a substantial challenge to adaptation.”
With all due respect to the renowned ingenuity of Californians, adaptation looks like a daunting task. And the risk is that belief in our technological capabilities to adapt to whatever comes our way might get in the way of a more comprehensive response, going well beyond California’s already ambitious renewable energy goals.
“I do think agriculture is an industry that is very resilient and adaptive,” said Kate Gordon, a senior adviser to the Risky Business project and the head of the Energy and Climate Program at Next Generation, which promotes the development of advanced energy. “But there is a limit to that.”
In coming years, Californians may find out what those limits really are.