What does a mountain lake reveal about California’s drought?

In findings consistent with previous research, a study found that past periods of drought in the American West aligned with climate warming and cool ocean temperatures in the eastern Pacific Ocean.

Melanie Stetson Freeman/The Christian Science Monitor
SAN LUIS RESERVOIR, MERCED COUNTY, CA - JULY 13: Water levels are extremely low in the San Luis Reservoir after a prolonged drought, on July 13, 2016 in Merced County, California. The reservoir is an artificial lake and the fifth largest reservoir in California. Water from the San Joaquin-Sacramento River Delta is pumped uphill into the reservoir and released to continue downstream along the California Aqueduct for farm irrigation and other uses.

One lake in California may hold clues as to how the state's current five-year drought and other major droughts throughout the region's history have been linked to climate change, hinting at what Californians might expect in the future, as well.

A study led by Glen MacDonald, a climate change researcher and professor at the University of California, Los Angeles, analyzed the relationship between past periods of climate warming, surface sea temperatures, and prolonged drought. And the findings, published on Thursday in Scientific Reports, could help determine if anthropogenic climate change will affect periods of drought in a similar way to historic, natural sources of climate change. 

"These data provide evidence of a persistent relationship between past climate warming, Pacific sea surface temperature (SST) shifts and centennial to millennial episodes of California aridity...despite differences in the factors producing increased radiative forcing," the authors write.

The research team analyzed the organic matter in the sediments of a lake in the Eastern Sierra Nevada mountains to determine the changes in its past climate and water conditions. They then correlated their findings, and those in similar studies, with data from Pacific Ocean marine sediment.

In findings consistent with previous research, the study found that past periods of drought in the American West, such as those that occurred between 5,000 and 1,000 BC and during the European Middle Ages, aligned with climate warming and cool ocean temperatures in the eastern Pacific Ocean. Cool ocean temperatures will exacerbate the effects of climate change in a La Niña-like event, according to the study.

"There is little new here," Martin Hoerling, a research scientist with the National Oceanic and Atmospheric Administration who was not involved in the study, told the Los Angeles Times. He added that existing climate models "do affirm, that when the east Pacific is cold compared to the remaining tropical [waters], the American West tends to have low precipitation."

It is still uncertain as to whether anthropogenic climate change will affect the Pacific Ocean, and subsequently the drought in California, the same way that previous climate change events have – from volcanic activity, to sun spots, to shifts in the Earth's orbit.

"We don't know how the Pacific Ocean is going to respond," Dr. MacDonald told The LA Times. "The climate models which we use … are very, very poor in predicting what is going to happen to the Pacific." 

But there is a possibility that California's current drought is only the beginning of a longer shift, the researchers say. If California does settle into an extended period of aridity, MacDonald has some ideas about what to expect, based on previous climate conditions.

"In a century or so, we might see a retreat of forest lands, and an expansion of sagebrush, grasslands and deserts," MacDonald said in a press release. "We would expect temperatures to get higher, and rainfall and snowfall would decrease. Fire activity could increase, and lakes would get shallower, with some becoming marshy or drying up."

You've read  of  free articles. Subscribe to continue.
Real news can be honest, hopeful, credible, constructive.
What is the Monitor difference? Tackling the tough headlines – with humanity. Listening to sources – with respect. Seeing the story that others are missing by reporting what so often gets overlooked: the values that connect us. That’s Monitor reporting – news that changes how you see the world.

Dear Reader,

About a year ago, I happened upon this statement about the Monitor in the Harvard Business Review – under the charming heading of “do things that don’t interest you”:

“Many things that end up” being meaningful, writes social scientist Joseph Grenny, “have come from conference workshops, articles, or online videos that began as a chore and ended with an insight. My work in Kenya, for example, was heavily influenced by a Christian Science Monitor article I had forced myself to read 10 years earlier. Sometimes, we call things ‘boring’ simply because they lie outside the box we are currently in.”

If you were to come up with a punchline to a joke about the Monitor, that would probably be it. We’re seen as being global, fair, insightful, and perhaps a bit too earnest. We’re the bran muffin of journalism.

But you know what? We change lives. And I’m going to argue that we change lives precisely because we force open that too-small box that most human beings think they live in.

The Monitor is a peculiar little publication that’s hard for the world to figure out. We’re run by a church, but we’re not only for church members and we’re not about converting people. We’re known as being fair even as the world becomes as polarized as at any time since the newspaper’s founding in 1908.

We have a mission beyond circulation, we want to bridge divides. We’re about kicking down the door of thought everywhere and saying, “You are bigger and more capable than you realize. And we can prove it.”

If you’re looking for bran muffin journalism, you can subscribe to the Monitor for $15. You’ll get the Monitor Weekly magazine, the Monitor Daily email, and unlimited access to CSMonitor.com.

QR Code to  What does a mountain lake reveal about California’s drought?
Read this article in
QR Code to Subscription page
Start your subscription today