Research by Scripps Institution of Oceanography has found that the 2015-16 El Niño caused major beach erosion and closed estuaries, even if it didn’t bring record rain.
It was supposed to be a record wet winter in Southern California, but precipitation levels barely made it to average in several areas, with the increased rain falling mainly in Northern California.
“It was clear that while El Niño had stacked the deck for a wet Southern California, it was still possible to draw the wrong card and that’s what happened in Southern California,” said climate researcher Marty Ralph, who directs the Center for Western Water and Weather Extremes at Scripps.
While the record Southern California rain didn’t materialize, this El Niño had a variety of other severe impacts.
“There’s a public perception that El Niño never came but it certainly did from an ocean perspective,” said Scripps coastal oceanographer Sarah Giddings, who studied its effects on Southern California estuaries.
The El Niño caused severe beach erosion, and closed estuaries up and down the coast. Storms sealed off the mouth of the Tijuana River from the ocean for the first time since the 1982-83 El Niño.
With sea levels were elevated as much as 11 inches above predicted heights between October and April, energetic waves consistently pounded the West Coast. Erosion on San Diego-area beaches ranged from 6.5 feet to 10 feet, compared less than six feet in a typical winter.
The rains that did come were unusually intense and caused flash flooding in some areas.
“This year’s El Niño brought less overall rainfall than expected; however, it did bring very intense rains over very short periods of time and at abnormal times of the year,” noted Laura Engeman, manager of the San Diego Regional Climate Collaborative, an information-sharing network of local cities, universities, and other entities.
“These rains led to severe flash floods in several cities across the region, exemplifying how these climatic shifts can impact our businesses and communities, and why it is important that we plan now to make us more resilient to the impacts of these climatic extremes,” Engeman said.
Scripps found that the El Niño effects were pushed westward much of the time by a persistent high-pressure ridge over the southwest, leading to new theories about how the phenomenon might behave in the future against a backdrop of global warming.