CARLSBAD, California, Sept 25 (Reuters) - In Malibu, the Pacific Ocean opened a sinkhole near the home of movie star Nicolas Cage and wreaked havoc on beachfront property. Along Beach Road in the city of Dana Point, waves destroyed one home and forced the city to vacate or restrict occupancy to 16 others.
Such damage up and down Southern California this summer was provoked by a series of Eastern Pacific cyclones and hurricanes, enhanced by the weather phenomenon known as El Niño. Although the hurricanes did not make landfall in California, they generated swells that slammed into the coast, denuding beaches of sand and transforming a coastline that is as much a part of California's identity as Hollywood or Silicon Valley.
Experts say even more ferocious waves could arrive in the coming months, when naturally occurring weather cycles, supercharged by climate change, could coincide with the highest of high tides.
"Things are definitely lining up for this to be a pretty epic winter in terms of potential hazards," said Patrick Barnard, research director of the Center for Coastal Climate Resilience at the University of California, Santa Cruz. "Everything's amplified by climate change."
California this week preemptively declared a state of emergency to help mobilize disaster relief and first responders in preparation for more turmoil from El Niño, which emerged in June. The phenomenon is expected to demonstrate its greatest effects through year end and into early 2027.
On Friday, another hurricane, Polo, churned off the Mexican Pacific coast. It could send more waves northward. Officials canceled the inaugural Ocean Way Festival set for this weekend in Santa Monica, after storm surf and runoff from Hurricane Marie over Labor Day weekend eroded much of the concert site just south of the pier.
El Niño occurs every few years, when surface waters in the central and eastern tropical Pacific Ocean become unusually warm, altering atmospheric circulation and weather around the world.
The Southern California sea level has risen 8 to 12 inches (20 cm to 30 cm) over the past century. A strong El Niño could temporarily increase the sea level another 6 to 12 inches (15 to 30 cm).
KELVIN WAVE AND KING TIDES
Related to El Niño is the underwater Kelvin wave, which could temporarily add another 6 to 12 inches in sea level. The first major Kelvin wave of the current El Niño is expected to reach California in early October, according to Michael Jacox, an oceanographer at the US National Oceanic and Atmospheric Administration.
The effects could coincide with seasonally extreme king tides occurring during the tide-amplifying phase of the 18.6-year lunar nodal cycle. El Niño could also produce massive rainstorms known as atmospheric rivers that often flood coastal areas and erode beach bluffs.
California's generally steep coastline has until now largely spared residents the chronic inundation seen in low-lying coastal areas elsewhere in the world.
In Carlsbad, a city of 112,000 about 35 miles (56 km) north of San Diego, the sand disappeared almost overnight from Tamarack beach, the jewel for a city that raises 14% of its operating budget from hotel room taxes.
Adam Young, a coastal geomorphologist from UC San Diego's Scripps Institution of Oceanography, visited Tamarack recently, climbing over cobblestones where there used to be sandy beach. Just to the south, the ocean swallowed the beach completely, cascading into a parking lot that once allowed visitors to park just a few steps from the sand.
Young said state and local government can attempt to harden properties, add sand to the beach, or form dunes out of the cobblestones, mimicking nature.
"There often isn't one solution that works for everyone," Young said. "It's important to remember that erosion on the coastline has been going on for thousands of years. It's a natural process. The problem is really that we build stuff in the way and on the beaches and in these hazardous areas, and that's caused the problem."
Surfers still flock to Tamarack. But a beach typically populated with tourists and locals now has only a few visitors who stake out a patch of what little sand remains.
"Hopefully they can figure out a solution because honestly, I think Mother Nature is going to take everything back until they stop it, right?" said surfer Alex Stott after a morning session. "It's showing it can take the entire beach if it wants to pretty quickly."
(Reporting by Daniel Trotta in Carlsbad, California; editing by Donna Bryson and David Gregorio)
