The past three years have been the driest such period on record in California, state officials said this week. The state is now preparing for the increasing probability that it will see a fourth consecutive dry year as it works to conserve water resources as reservoir supplies dwindle.
California’s water year, which ended in September, came with both wet and dry extremes, state climatologist Michael Anderson said during a news briefing early this week. Human-caused climate change has increased the potential for this weather whiplash, where dramatic shifts in between extremely dry periods and high precipitation can occur more frequently – and the phenomenon has been pronounced on the West Coast in recent years.
Anderson said the water year that just ended “certainly meets the narrative of climate change with more extremes and more variability.” Despite an overall improvement in drought conditions in the state, he said reservoir storage is now “slightly better than last year – but still well-below average.”
California has already been holding back water in its reservoirs in anticipation of more dry years to come. Global scientists reported last year that droughts that may have occurred only once every decade or so now happen 70% more frequently due to the climate crisis.
For the water year that just ended, Jeanine Jones, California’s drought manager, said the state had 76% of its average annual precipitation which lead to better reservoir storage numbers compared with the year before, which was abysmally dry.
“We are now consciously holding over more water in our reservoirs because we are more actively focused on planning for carryover storage for multi-year droughts,” Jones said.
And according to John Abatzoglou, a professor of climatology at University of California at Merced, a dry autumn is what they fear next.
“This would stall any buildup of mountain snowpack that is critical for large water systems in the Southwest and California and compress our window for bending the curve on the current drought in the upcoming water year to mid-to-late winter,” he told CNN.
Back-to-back La Niña
More than 73% of the West is currently in drought conditions, according to the US Drought Monitor. And although summer rainfall brought some relief to parts of the Southwest, the prolonged, multi-year drought there may persist with La Niña in the forecast for the third year in a row, according to the state’s Department of Water Resources.
“The La Niña forecast is about as auspicious for Southwestern drought relief as it was this time in 2020 or in 2021 – meaning not at all,” Justin Mankin, assistant professor of geography at Dartmouth College and co-lead of NOAA’s Drought Task Force, told CNN. “What’s pretty clear is that it is going to be hard to get the type of banner year for rain and snow we need to ameliorate this drought.”
La Niña is a natural phenomenon marked by cooler-than-average sea surface temperatures across the central and eastern Pacific Ocean near the equator, which causes shifts in weather across the globe. In the Southwest, La Niña typically causes the jet stream – upper-level winds that carry storms around the globe – to shift northward. That means less rainfall for a region that desperately needs it.
But experts also say that La Niña years can still be highly variable.
“I’d say there is little solid information suggesting that fall will be dry or wet as the La Niña signal tends to be a bit more pronounced in mid- to late winter, hence my general guidance would be for drought to persist,” Abatzoglou said. “Although, the deeper we go into fall or winter without meaningful precipitation and snowpack, the more drought is ratcheted up.”
Mankin said that in general, a La Niña year is “a harbinger of a dry winter” – and that forecast comes at a crucial time for Western states as they attempt to negotiate huge cuts in water usage, particularly from the Colorado River.
US Bureau of Reclamation Commissioner Camille Touton has called for Western states to come up with a plan to slash 2 to 4 million acre-feet of Colorado River water usage to protect the system from collapsing. States are still negotiating a voluntary agreement, but talks have been contentious and it’s unclear if or when they will produce a result that meets Touton’s goal.
“Water districts, farmers, ranchers and municipalities have been in a protracted crisis for about 34 months, stressing drought management and mitigation resources,” Mankin said. “Our largest reservoirs, Powell and Mead, are failing to perform their basic functions of hydropower and water supply, and none of the states sharing the water from the Colorado River, the most important basin in West, appear willing to restructure their allocations in the way the climate system is asking them to. So it doesn’t bode well.”
Jones said the state is planning for the drought to continue since it is impossible to know whether this new water year will be wet or dry. She added that this is necessary since the state is “on a trajectory toward warmer and drier conditions.”
“California is known for its wide variability in precipitation from year to year,” said Jones. “We should always be thinking about planning for a year in which we might see some very wet extremes or … another dry year.”
As the climate crisis advances, experts say the West will only continue to see more droughts like the present one in the years to come – and only rapid, immediate cuts to planet-heating emissions can halt this harsh trend.
“Whether these La Niñas have been bad luck or a response to climate change is less important than the fact that this drought has both been made worse by climate change and has revealed how poorly adapted we are to the climate we have,” Mankin said.
One thing is certain, he adds: “Another year of drought could potentially bring new frightening realities.”
CNN’s Ella Nilsen contributed to this report.