On Thursday afternoon, a group of Carlsbad High School students were surfing at Tamarack State Beach.
It’s part of their physical education class. But the shore looked different. Instead of sand, there were pebbles and rocks everywhere.
“To see no sand on the beaches sucks,” Kai Johnson said. “I surf a lot. So walking on these rocks really sucks. It hurts my feet.”
Tamarack lost most of its sand between August and September, in part because of the storm swells from Hurricane Genevieve.
“It’s pretty chaotic with the rocks and stuff, getting in and out of the water,” Finn Newnan said.
Multiple storms this summer battered Southern California, leading to several coastal communities, from Long Beach to Carlsbad, declaring a local state of emergency in preparation for a strong El Niño.
Weather experts said this could be the strong El Niño on record yet, which could worsen beach and coastal erosion.
“I think it's gonna damage more of the beaches — not just this beach, but also beaches down by Terramar and all those places,” Newnan said. And it's affecting the cliffs and everything. So I think it's something that’s going to cause an impact.”
But there’s a hidden danger from El Niño that most people don’t know about. It’s called the Kelvin wave. Normally the trade winds blow east to west, but during El Niño years, those winds die down.
“And when that slows down, that allows the warm water that's usually in the western Pacific, near Japan, to kind of sloshes back very slowly over to our eastern Pacific, where we are in San Diego,” said Eric Snortum, an oceanography and geology professor at MiraCosta College.
Scientists have known about Kelvin waves for years. They’ve always been associated with El Niño, but only now has it gotten public attention.
Unlike typical waves that crest and crash onto shore, Kelvin waves look more like a bulge of water sloshing back and forth in a bathtub. Snortum said that could raise sea level around 6 inches, which doesn’t sound like much, but it’s enough to cause severe damage.
“That allows for higher potentials for storms and therefore more consistent, potentially larger waves,” he said. “And those waves, high energy hitting the ocean, hitting our coasts leads to more erosion.”
It’s a cumulative effect. Warmer water means more water vapor in the atmosphere. That means more chances for storms and more beach and coastal erosion like Tamarack, with pebbles everywhere.
“I'm concerned that it will get worse,” Johnson said. “And with these big waves that the El Niño brings, I think it'll just keep getting worse.”
