The Prophet of California Climate: A Dialogue with Bill Patzert

The NASA Jet Propulsion Laboratory climatologist weighs in on the great water debate

We set out to have a question and answer session with Bill Patzert, a climatologist with Caltech’s NASA Jet Propulsion Laboratory in Pasadena. What we intended was a Q&A about how climate change will affect California’s water supply in the coming years. But the dialogue turned out to be something different: The veteran scientist had a lot to say. Rather than slow down Patzert, who’s been called “the prophet of California climate,” we gave him the mic instead. Here’s a slightly condensed version of his comments.

California: Wrong Place, Wrong Time?
If you fly from L.A. to New York, you notice that everything west of the Mississippi is brown and everything east of the Mississippi is green. The West has been dry for millions of years. And the population center of the country has switched from the Midwest and the Northeast to the Southeast and the West. In 1950 there were 4 million people in Southern California. Now there are 20 million. Totally illogical. Now, up until 1941, growth in Southern California and the San Joaquin Valley was slow. We were a backwater. Then they built Hoover Dam and Parker Dam and created Lake Havasu and the great Colorado Aqueduct, which brings water from the Colorado into Riverside. We distributed it all over Southern California, and growth was phenomenal in the ’40s and the ’50s. We hit the ’60s, and suddenly there wasn’t enough water. The great governor Pat Brown sponsored legislation to build the California Aqueduct, that thing that you see off to the right when you go up the 5 to San Francisco.

Now the California Aqueduct, coming from the Sacramento-San Joaquin Bay Delta, supplies 40 percent of the water to Southern California. The Colorado Aqueduct gives us another 25 percent. So 65 percent to 70 percent of our water is imported. Forget about climate change: What really counts is that the Colorado better not go dry and the Bay Delta better continue to supply us with our present allocation or better.

In Southern California and L.A., the average rainfall is 15 inches a year. That supplies enough water for about 5 million people, but right now there are 20 million people between San Diego and Santa Barbara. So all of us are either drinking Sacramento Delta water or Colorado River water. California depends on the biggest water infrastructure project in the world. There’s nothing like it anywhere else. Twenty percent of all the energy in the state of California is used to move water. Fifty percent of the energy generated at Hoover is used to move water from Lake Havasu to Hemet.

The Other Climate Change
And of course, the supply waxes and wanes with natural climate variability. Here in L.A. we go anywhere from 37 to 38 inches of rainfall a year—the maximum during a huge year like an El Niño year—to as little as 3 inches a year, which is what we had in 2006, 2007. Since the last big El Niño, which was ’97, ’98, there’s been a big shift in the Pacific with what’s called the Pacific Decadal Oscillation, which is a change in sea surface temperatures, so we’ve seen a lot of La Niñas and basically—except for a couple of years and a couple of big storms—it’s been dry here for more than a decade. But we muddled through because 65 percent of our water is imported. We often get decades or multidecades where it’s extremely dry. The ’50s and ’60s were extremely dry. Everyone will remember the Dust Bowl of the ’30s.

Our water supply depends on the snowpack in the northern Sierra and the eastern Rockies. It also depends on the population growth in the Southwest. We share the Colorado with seven states and six Indian nations. Everybody gets an allocation and we leave a couple of drops down at the bottom for Mexico. That’s the background info on water in the West. We capture it, we ship it.

Let’s look back over the last 20 centuries: We’ve seen tremendous droughts in the American West. In the 11th century there was an 80-year drought along the Colorado. This is before global warming by anthropogenic—or man-made—sources. The 20th century, which is when we built our civilization in California, was one of the wettest in 2,000 years. It was an anomaly. We know this from tree ring records. We have built a civilization, which is the sixth- or seventh-largest economy in the world, based on imported water in a wet century. How do you like that?

We have built a civilization in an extremely dry place. The limiting factor in any civilization is primarily water. Look at all the great civilization collapses. The 11th century is when the Anasazis had to disperse because of the 80-year drought on the Colorado. The same is true for many civilizations in Mesoamerica. This story can be told for the civilization that built Angkor Wat in Cambodia. It can be told in the Middle East. One of the primary determinates of human civilization has been drought: natural climate variability. We’ve seen this is our history. The history of the world is written in droughts.

So even without climate change, we’re pushing the boundaries here. We’re doing something that is pretty illogical. Take Beverly Hills. It looks like a rain forest. For a while here we had a plethora of water because the California Aqueduct and the Colorado Aqueduct were coming, and in 1950 there were only 4 million of us. They couldn’t sell enough water. The urban forest is maintained by the lawn sprinkling system. If you turned off your lawn sprinklers for two years, half the trees would die. That’s why when we have a windstorm, they all fall over: They’re shallow rooted. One big tree takes at least 50 gallons per day. In your water bill 75 percent of the water is for your yard. And all of us overwater our yards by at least six feet a year. We’re water pigs.

Getting Warmer and Warmer
Now, for climate change: In the last 150 years, CO2 has gone from 280 parts per million in the atmosphere to 400. CO2 was not at 400 parts per million 3 million to 5 million years ago. It’s the highest it’s been. The average temperature of the earth has gone up 1.6, 1.7 degrees Fahrenheit. That’s a lot.

Most of that heat that’s radiated from the warmer atmosphere is going into the oceans—like 90 percent. In the same period, sea level has risen 10 inches. Back in the 1880s and ’90s, the average temperature of the earth was about 56.5 degrees Fahrenheit. Now the average temperature of the earth is 58.1, and that’s not equally distributed all over the earth. You see it in the change in the seasons. For instance, in the California Sierra the snow season is measurably later than it was and it ends earlier, so that means less snowpack gets to stay. And the Sierra snowpack sort of stores water. It’s the Lake Mead of the Sacramento Delta. With a shorter snow season, more melt tends to run off into the oceans and less tends to soak into the ecosystems of California. It comes gushing out rather than soaking in. The mountains are getting warmer. The ecosystems are changing. Plants are shifting higher in altitude to follow the water. Many species are migrating. The whole system is changing.

The unequivocal proof of global warming is not only the 1.6 degrees, though: It’s the 10-inch rise in sea level. When you warm water, you expand water. Of course, you melt glaciers and ice sheets, too.

Will this warming temperature impact rainfall and snowfall? Will we see a fundamental shift? I just completed a study where I looked at 100 years of rainfall data. There was a slight tendency for more rainfall in Northern California and less in Southern California. Very slight. Some people say that the American Southwest will be drier and the American Northwest will be wetter. But I don’t say more than I know. Basically, I don’t believe the models. I know what their shortcomings are.

California’s Greatest Challenge
The biggest change is not a global warming-related increase in temperature. The biggest change stems from the extreme makeover we’ve done in California. In L.A., the average temperature has changed more than 5 degrees Fahrenheit in the last 150 years. And let’s compare that with the 1.6 global. The average temperature in the San Joaquin Valley has changed more than 5 degrees since 1950. Why is that? It’s called urban agricultural heat islands. The San Joaquin Valley makes up a third of California. And before the California Water Project—where we irrigated the whole San Joaquin Valley with the California Aqueduct—the average rainfall there was 5 inches a year. Now it’s irrigated from east to west, north to south. It’s the breadbasket of the United States. It’s responsible for 5 percent of the state’s economy. But when you take a desert, which the San Joaquin essentially is, and you make it wet, it starts to absorb heat. So now dangerous heat impacts are common in the San Joaquin Valley. Heat waves are longer; they’re more intense, they’re more frequent. So the direct impact of the population explosion and extensive development has had a bigger impact than global warming.

San Diego County has had a six-fold increase in population since 1950. It’s got 3.5 million people. In 1950, it was about 600,000. We’re talking golf courses, blacktop freeways, shopping centers, lawns. Lawns heat the city up. Trees cool them off, but lawns heat them up.

The problem is population. It’s having a bigger impact on the Southwest than climate change. So far. But most of the impacts that people project are negative: More population, higher demand, less snowpack—that means less supply coming down the Colorado and the San Joaquin and Sacramento rivers. As the population increases, it becomes more affluent; there’s more and more technology. Everything goes up. Here at JPL, we are anal about energy and water usage. But it’s gone up, on average, 10 to 15 percent every year for the last decade. Why is that? Servers and the air conditioners for them. It’s called the I=P x A x T formula: human impact equals population multiplied by affluence multiplied by technology.

Climate change is one factor in the equation, but you have a lot to learn from what already happened. The great robber barons and the great politicians gave the West a tremendous water infrastructure, but they also gave us a tremendous thirst for water and power that wasn’t very energy efficient. It’s a hot, dry place. All these things will continue and multiply. And on top of that, we will have more impacts on snowpack, river flow: Climate change will definitely be the straw on the camel’s back—climate change will be the back breaker. It’s the game changer.

Dry Winters, Dirty Water
Even without climate change, the situation is going in the wrong direction rapidly. A big part of the water scenario are the aquifers and groundwater in California. As the great glaciers receded north, they left tremendous supplies of gravel [where water can reside]. They can be a half mile deep, a quarter mile deep. The great glaciers never impacted San Diego County. So they have no groundwater supply. That’s why they have to do 95 percent. Whereas the San Joaquin Valley and the greater Los Angeles Basin, including the Inland Empire and the San Fernando Valley, had the great glaciers that left tremendous gravel deposits, which are now groundwater basins.

Historically they’ve been a big part of the water supply and driven agriculture and other things. They’re sort of your reserve tank, just in case. When you put a well into an aquifer, you can also reverse it and actually pump water into it. So you can use it to store water. It’s like having a tank in your backyard. All across the American West and an international problem, the great aquifers are being drawn down and not replenished. For instance, there are places in the San Joaquin Valley—the subsidence (when you pump out the water, the land collapses)—that have gone down 30 feet since the beginning of the century.

L.A. has actually got a big groundwater aquifer system. Historically, we’ve imported so much water here in the last 50 years that we’ve neglected our groundwater basins. An awful lot of local aquifers are polluted. But now there’s a realization that during the flush years we could capture a lot more water and store it beneath our cities and communities. For instance, Sierra Madre, where I live, has been 100 percent independent of imported water because we had a good groundwater, or aquifer, supply beneath the community. But three of our six wells just went dry because it’s been a dry decade, and this winter was unusually dry.

This was the sixth driest winter in the last 135 years in Southern California. And for the whole state, the thing that really killed us is that it stopped raining after December. Three-fourths of the rain and the snow usually happen after January. So there was a realization that we have to clean up the aquifers, or what I call the groundwater basins, in Southern California and elsewhere.

I think many communities right now get about 50 percent of their water from groundwater. I would say that we could go from, if we really cleaned up our groundwater systems—a process that’ll take decades; we could go from a 70 percent dependence on imported water, dropping that to maybe 30 or 40 percent; I don’t have the numbers, but let’s say we could halve it. For instance, we could open up the L.A. River, the Santa Ana River, the San Gabriel River, and capture more of the water.

The Army Corps of Engineers concreted the L.A. River after everything south of downtown L.A. flooded in 1938. It’s a superhighway to transport water from the San Fernando Valley, the San Gabriel Valley to the ocean, as quickly as possible. The guys that designed that were brilliant. It’s an engineering feat, but most people don’t think of it that way. The L.A. River, the Santa Ana, and the San Gabriel—they’re flood control channels. They’re not rivers. The L.A. River is concreted for 51 miles from the San Fernando Valley to the Aquarium of the Pacific, and it’s got 1,600 miles of storm sewers connected to it. We could slowly create catchment basins along these rivers to replenish the groundwater basins beneath. And we could make them more friendly to the urban community than the L.A. River is today.

Another thing about water is there are literally hundreds of community- and city-based water districts, from tiny ones to monsters. The management and the trading back and forth of water is almost medieval in the way it’s done. Some farmers in the Central Valley actually don’t use their land for a year or two and store their water allocation from the State of California. Then they sell it to the City of Los Angeles or Orange County or whoever. The price fluctuates depending on how much water there is, how much drought there is. It’s a billion-dollar business. My recommendation is that there should be a water czar in California so that we can have a consistent policy where the little guys and the big guys all get treated equally. Right now it seems that agriculture gets the unfair share. Even though agriculture [makes up] about 5 percent of the economy, the state has changed in the last half century. We’re more urban.

Water Is the Past, and It Will Be the Future
Climate is a 50-year thing. Population and its impact on the world was the last hundred years, and it’s been immense. The biggest thing is that the human footprint has just become immense. We’re in the age where we are seeing the biggest extinction of species. We’re doing an extreme makeover on the surface of the earth. Rain forests are disappearing. A lot of people don’t realize that 20 percent of global warming is deforestation, and most people don’t understand that they’re building their future around water. Our history is water and our future is water. And it’s a damn dry place. Are we running out of water? My answer is, Not anytime soon, even with climate change. But we will have to manage and use it differently than we do today. Managed and used wisely, our fantastic water delivery system is good for another 50 years!

This article has been updated to more accurately reflect certain statistics.

Water in L.A.