New research says climate change could be recreating prehistoric conditions, turning California into a desert.
Dry riverbed in California. Image: National Oceanic and Atmosphere Association/Wikimedia
California's five-year-long drought has already had punishing effects—stronger fires, dying Redwoods and lots and lots of brown lawns. Now, experts say, this could be the "new normal".
Scientists at at UCLA reported that the effects from greenhouse gases could cause the drought to last for centuries, according to a paper published in Nature.com's Scientific Reports. "When you have arid periods that persist for 60 years, as we did in the 12th century, or for millennia, as we did from 6,000 to 1,000 B.C., that's not really a 'drought.' That aridity is the new normal," study leader and UCLA professor Glen MacDonald said in a release.
The researchers took dirt samples from Kirman Lake in the Sierra Nevada mountains to see how the state's climate had waxed and waned over thousands of years. They found that whenever a strong external force changes weather patterns over a long period of time, California's location means it bears the brunt of those changes—usually by drying out.
Effects like sunspots, a slightly altered Earth orbit, and decreased volcanic activity changed California's weather for hundreds of years. One dry period lasted from 950 A.D. to 1250 A.D. due to increased sunspots (which are dark spots on the sun that reduce the surface temperature) and fewer erupting volcanoes—300 years of thirsty land.
This is because changes in ocean temperature caused by these events radically affected how much rain California receives, researchers suggested. Being on the Eastern edge of the Pacific Ocean, California is subject to alternating rain systems: El Niño and La Niña.
El Niño brings lots of rain, but it requires warm Pacific conditions. La Niña brings far fewer storms and mostly dry wind, and it forms when the Pacific is colder. And due to the effects of greenhouse gases, the Pacific Ocean has been slightly colder than its historic average in recent years.
The paradox of climate change is that as some areas get warmer, others get colder. And it messes up the entire world's weather. That being said, the International Panel on Climate Change stated in 2013 that it believes the El Niño-La Niña cycle will continue—with the caveat that they aren't sure yet how climate change will affect the frequency of that cycle or the strength of each.
Without regular El Niño storms—or even without a break from the rain-suppressing La Niña systems—California will keep getting dryer, according to the release. And humans are vulnerable from stress factors such as a lack of water.
"I think we would find a way to keep our cities going through prolonged drought, but we're not going to engineer a way to conserve or preserve the ecosystems of the state," MacDonald said. "We can't save our huge expanses of oak woodlands, or our pine and fir forests, or high-elevation alpine ecosystems with irrigation projects like we might our orchards and gardens."
He said the effects could be disastrous to California's lush, green forests, like the ones that typify Yosemite National Park and the Sierra Nevadas.
"In a century or so, we might see a retreat of forest lands, and an expansion of sagebrush, grasslands and deserts," MacDonald added. "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."
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