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Troubling View From the Oasis: California's Abundance May Be a Mirage 

Wednesday, Mar 5 2014
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The 20th century saw the construction of massive engineering projects that set up the labyrinthine water infrastructure that exists today. It was an age of men gleefully manipulating the natural world, moving water from places that had it to places that didn't. The state was girdled with impressive public works: dams, aqueducts, hydraulic pumps, all the systems that we still use, including the California Aqueduct that brings water from the Sierra down through the Central Valley and over the Tehachapi Mountains to Los Angeles.

The drought of '76-'77 and another in '87-'92 ushered in a new age: environmental conservation instead of manipulation. Part of it was geographic reality: California didn't have many choice river sites left to dam up. Part of it was a growing population: The state had 7 million residents in the 1930s, 31 million in the 1980s, and the need for much more water. And policymakers started seeing that even with all the infrastructure they'd developed, shortages still occurred. "We'll never drought-proof California," says Jay Lund, head of the Center of Watershed Sciences at UC Davis. "It's the nature of our climate. Just like the East Coast will always have hurricanes and the Midwest will always have tornadoes."

After the droughts of the latter half of the 20th century, policymakers realized that in some cases it was cheaper to conserve the water that we already had than to go out and try to find more. Lund compares it to another issue in urban life: transportation. "We all get caught in traffic from time to time, but we never think we should build the freeways so big we never have more traffic jams," he says. Instead we put in HOV lanes and encourage carpooling, we take Caltrain and BART, we try not to tax the already taxed infrastructure any more than we need to.

The '70s drought video ends with a call for continued vigilance from the head of the agency, pleading with the public to not let the lessons of the drought fade from memory. "If we have learned our lessons well, the effects of future droughts need not be so traumatic," says the then-head of the Department of Water Resources from behind his desk, '70s brown suit and shaggy hair and all. "It is likely that there will be more dry years in the future."

They didn't know quite how likely. Since that video was made, paleoclimatologists — looking at thousands of years of climate history through tree rings and sediment samples — have uncovered evidence that the 20th century was perhaps an abnormally wet century in California. If that's true, it means that more dry years in the future aren't just a likelihood, they're an inevitability.

A Thousand Years Says a Lot About a Place

When we say California has a half-dozen big storms in a "normal" year, we're using a definition of "normal" that's been developed since the state started keeping records in 1850. A century and a half is four or five generations in human time, practically an eternity. But it's barely a ripple in global time. And evidence has been uncovered that suggests that California's "normal" is much drier than the 20th century led everyone to believe.

Paleoclimatologist and author B. Lynn Ingram was a geology Ph.D. student at UC Berkeley in the '80s studying core samples of San Francisco Bay. She was looking for big shifts in glacial and interglacial cycles — weather mood swings in the region that lasted thousands of years — when she and her colleagues found a curious thing. Instead of these large-scale shifts in climate, they found that the region's weather was much more variable. It swung between wet and dry in 10- and hundred-year cycles instead of thousands.

The bay acts as a drain for about 40 percent of the state's water; it's saltier in drought years and fresher in flood years. When the phytoplankton and mussels that live in the bay die, they sink to the bottom, where they become fossils. By pulling out long cylinders of sediment and analyzing the chemical content of the fossils, Ingram has a pretty good picture of which years were dry and which years weren't. And she and her team discovered that severe droughts, ones that lasted way beyond the six-year record of the 20th century, were far more common than previously thought.

Around the same time, fellow Berkeley Ph.D. student Scott Stine was looking at tree stumps that had emerged from the shrinking shores of Mono Lake in the Sierras during the late-'80s drought. Some of these trees were more than 160 years old, which meant that the shoreline had been low for at least that long. He carbon-dated the stumps and compared notes with Ingram. They realized that San Francisco Bay was saltier in the same years that the trees had grown: during two long, dry periods during A.D. 900-1100 and 1200-1400, together called the Great Medieval Drought. That's the same major drought that historians think could have ended the Anasazi civilization and others in the Southwest. And it means that the six-year droughts of the 20th century were nothing compared to what has come before.

But even the medieval megadroughts had nothing on the granddaddy of California dry spells, the not-so-creatively named "Long Drought" that started more than 6,000 years ago. The Long Drought was discovered by carbon-dating more submerged tree stumps in Lake Tahoe as well as stumps from other lakes in the Sierra; it spanned more than a thousand years.

Both of these seem so far back that they might as well be myth, but consider this: Both megadroughts occurred when the planet's overall temperature was warmer, which led to less snowpack in the Sierras and less water all around, conditions that could occur in the next few decades if climate change scientists' predictions are correct. Look at how much havoc even a three-year drought has wreaked. S.F.'s endured this myopia before, back in 1906, when its makers realized they had misread what nature was capable of.

About The Author

Anna Roth

Anna Roth

Bio:
Anna Roth is SF Weekly's former Food & Drink Editor and author of West Coast Road Eats: The Best Road Food From San Diego to the Canadian Border.

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