Pacific tropical storms and hurricanes with record-breaking energy are battering the Southern California coastline.
Researchers at Colorado State University confirmed Monday that this summer’s storms generated higher levels of cyclone energy accumulation than ever before, surpassing the seasonal record set in 2018. This metric is a measure of the total wind energy, intensity, and duration of tropical storms and hurricanes.
“It’s been a wild season,” said Daniel Cayan, a climate researcher at the Scripps Institution of Oceanography at the University of California, San Diego, noting that parts of the Southern California coast have already suffered severe damage ahead of the coming winter storm amid the strongest El Niño on record.
The historic Long Beach boardwalk buckled after a series of storms last month. Tropical Storm Rachel approached the coast over the weekend, with powerful waves slamming into beachfront homes, leaving some on the verge of collapse.
In Newport Beach, before Rachel arrived, huge waves – twice as large as initially predicted – breached the 20-foot-high berms erected on the beach and flooded the road.
Elsewhere along the coast, above-normal sea levels and the constant pounding of strong waves washed away sand this summer, profoundly altering the wedge of Newport Beach and beaches in San Onofre, Laguna Beach and San Clemente. The damage along the coast has been so severe that Orange County declared a state of emergency last month.
Daniel Swain, a climate scientist at the University of California, Agriculture and Natural Resources, explained in a recent webinar that the Pacific’s unusually active hurricane season is influenced by multiple factors, including long-term ocean heating trends from global warming, higher nearshore ocean temperatures, and reduced wind shear from El Niño, which can significantly weaken hurricane activity.
“El Niño in the Pacific basin reduces wind shear, so it removes the dampening effect of wind shear on storms and increases water temperatures,” Swain said. “So it adds more fuel and makes it more likely that the fuel will take advantage of its environment.”
Typically, storms weaken significantly once they enter the cooler waters of the eastern tropical Pacific. But marine heat waves and El Niño, which makes ocean temperatures 10 to 13 degrees warmer than normal, provide a more favorable environment for hurricanes like Rachel to get close enough to impact the California coast.
Combined with high tides and Kelvin waves, these storms can raise background sea levels by 6 to 12 inches, wreaking havoc and reshaping the coast during the summer.
Experts say it’s not over yet.
Hurricane Simon is currently spinning on the west coast of Mexico, where it is expected to make landfall this week, and forecasters say there is about a 90 percent chance it will form again within the next seven days.
“I wouldn’t be surprised if we see more hurricanes or tropical systems in the central and southern Pacific,” said Kristan Lund, a meteorologist with the National Weather Service in Oxnard.
Southern California is also gearing up for the El Niño phenomenon this winter.
The National Oceanic and Atmospheric Administration’s Climate Prediction Center said last week that there is almost a 100% chance that this season’s El Niño will be classified as “very strong.” There is an 83% chance that this El Niño will be the strongest on record since 1950, up from the 75% chance predicted last month.
Even if El Niño doesn’t cause heavy rains, it can wreak havoc on coastlines.
Beaches typically go through seasonal cycles, with strong winter waves dragging sand out to sea and summer waves depositing sand back onto the shore. But El Niño winters typically bring stronger waves, leading to more sand loss and erosion.
“There could be quite profound impacts along the coast,” Kayan said of the coming months. “There [are] There’s also cliff collapse and other impacts that occur when these big waves are higher and more active than normal, so there’s a lot of concern about that. “
The two strongest El Niños of the past 75 years (1982-83 and 1997-98) caused widespread damage along the Southern California coast, destroying homes, flooding streets and destroying piers.
The other, in 2015-16, did not have above-average rainfall but did cause record coastal erosion. That winter, researchers determined that waves were about 50 percent more extreme than normal and beach erosion was 76 percent greater than normal.
“We’ve had a few fairly active winter storms since the very big winter of 1983, but we’ve dodged bullets because these storms generally don’t occur at the highest tides,” Kayan said. “So it’s going to be another lucky draw this winter.”
This winter, California could see significant coastal erosion, flooding and damage if El Niño-driven storms arrive during king tides, Kayan said. King tides are expected during El Niño during Thanksgiving, Christmas and late January, with water levels likely to exceed 7 feet or more.
“These periods are really critical to the fate of California’s coastline and infrastructure this winter,” Kayan said.