Saturday, September 24, 2016

Drought In California: The Dry Years to Come

We have had dozens and dozens of posts on drought but if I had to pick only one concept to stress it would probably be our introduction to 2015's "The Economics of the California Water Shortage":
Where this gets really interesting is when you throw a historical perspective on the current California drought:
-San Jose Mercury-News "California drought: Past dry periods have lasted more than 200 years, scientists say"

That little red blip at the far right side of the timeline is the current drought.
You could make a reasonable argument that for the last 150 years Californians have been living in a fool's paradise....
And today's story, from LA Magazine, October 20, 2015:
With a growing population and warming climate, our water problems won’t be solved by one el Niño

It was the late summer of 1991, and California was deep into one of the worst droughts in its history. For five years with only scant interruption, the sky had burned hot and blue from November through March; bathtub rings on reservoirs rose high on their sun-parched walls. Water masters were panicking: The City of Santa Barbara built a plant to strip the salt from seawater; Los Angeles swiped images from Alfred Hitchcock’s Psycho for television ads to make people think twice about lingering in the shower.

Everybody I met talked as if the dry season would go on forever, and having only recently relocated from Minnesota, I believed them. “Remember when we used to have winter?” a woman in my office lamented to no one in particular. “We used to get so much beautiful rain.” Winter had gone the way of the downtown punk scene, Googie diners, and speedy trips along the 101. It was a symbol of what Los Angeles used to be, a figment whose memory causes a contraction in your heart, in the place where you feel longing and sadness for times gone by.

If only my new friends had paid closer attention to the distant forecast. Even as they spoke, a warm southern current was forming in the equatorial Pacific, where tropical storms gather strength to blast north toward the California coast. The sea-surface heat would build through the summer and fall, peaking around Christmastime, hence its name, El Niño, bestowed by 19th-century fishermen in honor of the baby Jesus. In October storms would uproot the big yellow umbrellas the artist Christo had installed that season in the Tehachapi Mountains; late December rainstorms would rage through January. In February of 1992, six inches of rain would fall in three hours, sending swift-water rescue teams scurrying to save flailing victims from the Los Angeles River.
Inside the Orange Counter Water District’s water recycling facility Photography by Spencer Lowell
Naively I had assumed that, despite the calamity the storms caused, the city would welcome the relief from drought. But the floods did us little good. City reservoirs, already full of imported water, weren’t situated in the right places to capture runoff from the streets. Instead billions of gallons of freshwater would empty each rainy day down storm drains to the ocean.

“We need these kinds of storms up in Northern California, where our reservoirs are,” Robert J. Gomperz, then spokesperson for the Metropolitan Water District of Southern California, explained to The New York Times. “Down here we have no way of capturing the water.” It would be another wet winter before snow returned to the mountains and officials declared an end to one more California water crisis.

Twenty-two years later, we’ve been forgetting winter again. In 2014, El Niño simmered in the Pacific through May and June but shriveled in July, abandoning the state to a fourth year of record-low reservoirs. Central Valley towns have run out of water; city lawns and leaves have gone brown. Santa Barbara has dusted off its desalination plant, the one that was shuttered in 1993 without delivering a drop of freshwater.
Once again relief might be brewing around the equator: El Niño is back, and it looks like a doozy. “Right now it’s on track to be as big as the El Niño of 1997 to 1998, which was the strongest one of the 20th century,” says Michael Dettinger, a research hydrologist with the U.S. Geological Survey and Scripps Institution of Oceanography in San Diego. February 1998 remains California’s wettest on record.
Strong El Niño years herald what meteorologists call atmospheric rivers: low-elevation ribbons of tropical moisture that can drop more than a third of the state’s water supply in a few weeks. (In the winter of 1861 to 1862, when floods and blizzards spread from California to Utah, an epic atmospheric river hammered California for 43 days.) Were that much precipitation to hit the ground as rain, the state’s storage network, vast though it is, wouldn’t be able to handle it. So hydrologists hope the storms cross the high peaks of the southern Sierra Nevada, where rain turns to snow and stays frozen until spring. “We call the snowpack our biggest reservoir,” says Ted Thomas, spokesperson for the California Department of Water Resources. “It meters water as the snow melts over several months.”

If, that is, the mountain winter gets cold. The spring before last at Phillips Station, 6,800 feet up in the Eastern Sierra where officials from the Department of Water Resources gauge the snowpack, only a quarter of the average snow had accumulated. This April a grim-faced Governor Jerry Brown had his picture taken planting the measuring pole atop dry grass. Yet both years were far from the driest we’ll ever have. In 2015, the eight mountain outposts that matter most received an average of 75 percent of their normal precipitation. “The problem was that both years were record-breakingly warm,” Dettinger says. “That warmth completely wrecked the snowpack.”

Like many atmospheric scientists, Dettinger is reluctant to categorize what we’re experiencing as climate change. California weather, orchestrated by a weather pattern known as the Pacific Decadal Oscillation, has always gone through dramatic cycles in normal times; balmy winters, they happen. But with heat-trapping gases building up in the atmosphere, we might consider 2015 a rehearsal for 2055. “This is what climate change will look like,” he says. “This is what a normal year will look like. Eventually the snowpack will disappear.”

Clearly more has to be done with what falls from the sky, something beyond directing our laundry runoff to fruit trees in the backyard. Worthy as our #droughthacks might be, none of them are enough to replace the snowpack on which Los Angeles depends for at least 80 percent of its water. Eastern Sierra meltwater from the Owens Valley and Mono Lake pours into the Los Angeles Aqueduct, which Mayor Fred Eaton and city engineer William Mulholland built to irrigate the city more than 100 years ago. Pumps direct freshwater from the Sacramento-San Joaquin River Delta into the California Aqueduct before it can get to San Francisco Bay. The Colorado River, too, finds its way to the city’s taps via the Metropolitan Water District, founded in 1928 to stake Southern California’s claim to that waterway.

All those sources come from fragile ecologies that have been brought to the brink of collapse by decades of water diversions; all are contested—by local communities, environmentalists, fishermen, competing users. All of them reach us along aqueducts that intersect earthquake faults, where a cataclysmic shudder could cut off supply. When Mayor Eric Garcetti last October ordered the Los Angeles Department of Water and Power to halve the city’s water imports within the next decade, he echoed a goal the utility’s managers had already set forth—and one that’s been long overdue: to remake the city of 4 million on a semiarid coast into a civilization that can survive the next century, starting with water....MORE
Seriously, always remember: "California: The Last 200 Years Were The Happy Time For Weather, Get Ready For A Return to The West Without Water". 
Straight Talk on Weather and Climate: "Will California's Drought Bring About $7 Broccoli?" 

Two quick points:
1) The Great American Desert was called that for a reason. The weather of the U.S. over the last 150 years is an anomaly in the longer history.
2) The subsidization of row crops, corn in particular, is a political decision that severely distorts investment and thus nutrition outcomes....
Finally, some good news:
Modeling: "In virtual mega-drought, California avoids defeat"
El Niño: "The ARkStorm Scenario Could Flood California's Central Valley like a Bathtub and Cost $725 Billion" 

On second thought maybe that last post shouldn't be in the good news file.