El Niño has arrived and it could become one of the largest on record, and California may be in for a bumpy ride.
While the climate pattern is often linked with a higher chance of more rain in Southern California, it can affect the state — and its famous coastline — in numerous ways. That’s especially possible during a strong El Niño event, as this one is shaping up to be.
In fact, there’s a 63% chance El Niño could be “very strong” toward the end of the year, according to the National Oceanic and Atmospheric Administration’s Climate Prediction Center. And there’s an 88% chance El Niño will be either “very strong” or “strong.”
“The recently observed and ongoing rapid escalation of conditions in the tropical Pacific, plus the consistently and increasingly extreme forward-looking model projections, truly do suggest that something extraordinary could unfold,” Daniel Swain, a UC climate scientist, wrote in a blog post.
“The upcoming El Niño event — which has a high likelihood of becoming very strong or even historic in magnitude — will likely lead to widespread and significant global impacts,” he added. “It is possible, even probable, that at least some of these effects will be unprecedented in the modern era, given the combined effects of a high-end El Niño event plus over a century of accumulated global warming.”
El Niño’s impacts are usually felt strongest during the winter. Here are five major ways California could be affected.
1. Wet and wild winter
While it’s no given, El Niño could open up the atmospheric floodgates in Southern California.
Of the last four “very strong” El Niños on record, two — 1982-83 and 1997-98 — brought coastal Southern California more than double its typical annual rainfall. Another, in 1991-92, brought 133% of the average, according to data provided by Jan Null, adjunct professor at San José State University. But the last one — in 2015-16 — did not meet expectations, with just 77% of the annual average rainfall in the Southland.
According to NOAA, stormier weather is generally more likely in the southern United States during an El Niño. The Pacific Northwest, on the other hand, generally gets drier winters.
“A very strong El Niño event might well be the single most important predictor of substantially increased odds of unusually wet conditions, and increased likelihood of individual heavy precipitation events, in any given winter in California — and perhaps also an early warning indicator of increased risk of large-scale flood events,” Swain wrote.
Despite the threat of floods, a wet winter could bring some relief to the Colorado River basin, which is in an “exceptionally severe multi-decadal drought,” Swain wrote.
2. High-tide flooding
More high-tide flooding is possible in an El Niño.
“Elevated sea levels along the West Coast of the U.S. can occur, causing high tides and strong surf to ride higher and push much further inland than normal,” NOAA said in a statement.
Agency experts noted that the El Niños of 2015-16 and 2023-24 brought more frequent, deeper and widespread high-tide flooding, a risk made worse after decades of sea level rise.
A man on a bike with his dog cross through a flooded Greenock Lane after the area was inundated during heavy surf at high tide on Dec. 28, 2023 in Ventura.
(Brian van der Brug/Los Angeles Times)
The El Niño of 2015-16 brought “record coastal erosion along many California beaches,” according to the California Coastal Commission.
“Major El Niño events can raise local sea level by around six to 10 inches in California during the winter rainy and stormy season through a combination of northward-propagating coastally-trapped Kelvin waves and thermal expansion of seawater,” Swain wrote. “Significant coastal flooding is possible later this year.”
3. Warmer waters and temperatures
One of the ingredients of El Niño is triggered when the trade winds in the Pacific Ocean — winds that reliably blow from east to west — weaken. That allows the sea level to rise a little bit, “and it creates what we call a downwelling oceanic Kelvin wave,” said Jon Gottschalck, the Climate Prediction Center’s operational prediction branch chief.
That’s not an ocean wave at the surface but one that moves warmer water at the surface deeper down. And the wave “will bring warm water from the western Pacific to the central and eastern Pacific,” Gottschalck said.
The next ingredient to an El Niño is seeing how the movement of warmer water eastward changes wind patterns.
Warmer water moving from west to east also decreases the west-to-east winds, which then allows even more warmer western water to move toward the eastern Pacific. “It’s kind of a positive feedback. And so once that occurred, the El Niño event will basically develop and intensify,” Gottschalck said.
The El Niño-triggered warming of water off the coast of Mexico, Central America and northern South America then typically moves the atmospheric jet stream southward to the southern United States, “which can bring wetter-than-normal conditions to our area” in the winter, said Ariel Cohen, a meteorologist at the National Weather Service office in Oxnard.
El Niño will probably contribute to more record-breaking global temperatures, Swain wrote.
(Paul Duginski / Los Angeles Times)
4. Sharks and other sea creatures
The warmer waters could attract additional seafaring tourists toward California’s shores.
“In the near future, we may expect to see an increase in tropical or warm subtropical species, which may include increased shark sightings off of the Southern California coast,” said Nate Jaros, the Aquarium of the Pacific’s vice president of animal care for fish and invertebrates. “In very rare cases, even whale sharks have visited off Catalina, including in the 2015-2016 El Niño events.”
Marine mammals and other migratory species may also move closer to shore, “because they’re going to where their food is,” said Andrew Leising, a research oceanographer at the National Oceanic and Atmospheric Administration’s Southwest Fisheries Science Center.
El Niño has in the past been associated with larger sablefish found closer to shore, and a higher larval abundance of rockfish.
Warmer ocean temperatures can also increase the presence of sea jellies and other gelatinous creatures, Jaros said.
A jellyfish-like creature called Velella velella, also known as by-the-wind sailors, can wash up on West Coast shores and are usually harmless to people. However, “in past El Niño events, we’ve seen similar-looking Portuguese man o’ war, a very rare visitor to our waters, washing up on our beaches. These animals can have a very painful sting,” Jaros said.
In a previous marine heat wave called “The Blob,” which was followed by a very strong El Niño, scientists observed increased tuna come closer to shore, go farther north, “and come in earlier than they do in other years, and so that actually leads to increases in fishing opportunity for those highly migratory and large game fish species,” Leising said.
5. But other sea life could struggle
While not solely the work of El Niño, warmer oceanic waters can wreak havoc on ocean life.
There are currently two marine heat waves unrelated to El Niño near California — one just off the state’s southern coast that started in December, and another farther west off the coast of Northern California and Oregon that started in May, according to data shared by Leising.
There are two marine heat waves off the West Coast currently, neither of which are being influenced by El Niño at this time. One is just off the Southern California coast and another farther offshore and west of Northern California and Oregon.
El Niño also tends to cause marine heat waves, Leising said.
“One of the most important things, though, for the animals in the ecosystem is not necessarily just how hot it is — that is important in some cases — but just how long they’re exposed to the heat,” Leising said. “We have a situation, particularly in Southern California, where we’ve already had this marine heat wave, and we’re just gonna kind of roll on into a heat wave that’s been brought about by El Niño.”
Past marine heat waves have decimated California’s kelp, “with bull kelp habitats declining 90% in Northern California since 2014,” Jaros said.
“The effects of this decline trickle down to other species, including endangered white abalone. And warmer waters can exacerbate the effects of sea star wasting disease, especially on the sunflower sea star, a population that’s nearly been wiped out of California,” he said.
In past strong El Niños, scientists have observed decreased plankton — an important food source for marine animals — and an increased probability of harmful algal blooms.
Previous strong El Niños have also brought a lower abundance, and a more northward shift, of market squid, Leising said.
“We often have seen in the past with El Niños reduced productivity of California sea lions, and the pups are often smaller,” Leising said.
A previous combination of “The Blob” — which hit the West Coast more than a decade ago — followed by a very strong El Niño resulted in “several closures of crab and shellfish fisheries due to harmful algal blooms,” according to Leising.
“We had increased whale entanglements because the whales, again, are closer to shore, they’re coming into contact with more ships and more fishing gear,” Leising said. “And we also had a loss of some of the habitat for groundfish because the oxygen at the bottom, where they live, was lower.”
There were also die-offs of seals, sea lions and marine birds, Leising said, probably from a combination of a lack of food and harmful algal blooms, and less food out there for baleen whales.
