Scientists warn of strong El Niño impacts on Southern California
Experts at a Scripps Institution conference said this year's El Niño is shaping up as one of the strongest on record, bringing higher ocean temperatures, increased flood risk and potential coastal erosion.
Scientists gathered at the Scripps Institution of Oceanography in La Jolla to assess the likely impacts of a powerful El Niño on Southern California. The event, hosted by the University of California San Diego, highlighted that the warming of Pacific waters and a stronger atmospheric jet stream raise the probability of prolonged atmospheric rivers that can deliver large volumes of rain.
"El Niño only sets that stage and tilts the odds toward more extreme weather," said Julie Kalansky, a climate scientist at Scripps.
Kalansky noted that while moderate precipitation could help reduce wildfire risk and replenish reservoirs, excessive rain may cause flooding, erosion and damage to the fragile coastline. The National Weather Service forecast office in San Diego cautioned that reliable predictions extend only about ten days out, with higher confidence for three- to four-day windows.
Ocean temperature records from the Scripps Shore Stations Program show surface waters well above the long-term average, with October readings ranking in the top ten percent of the 110-year record. Oceanographer Melissa Carter said the warm water reduces chlorophyll and phytoplankton, affecting marine food webs and slowing the growth of giant kelp.
Physical oceanographer Daniel Rudnick explained that warmer water expands, adding an estimated six to twelve inches to background sea levels, which could exacerbate the region's seasonal king tides scheduled for late October through January.
Coastal geomorphologist Adam Young warned that the combination of high tides, storms and elevated sea levels increases the risk of coastal flooding and erosion. Recent incidents along the San Diego County shoreline—including damage to streets in Oceanside, closures on Carlsbad Boulevard and erosion at Carlsbad State Beach—illustrate the vulnerability of local infrastructure.
Municipal officials from cities along the coast have begun reviewing flood-response plans and clearing drainage systems in anticipation of the forecast. Rail corridors that run close to the shoreline, such as the LOSSAN route through Del Mar and San Clemente, also face heightened risk of landslides and service disruptions.
Long-term mitigation plans include relocating vulnerable rail segments inland, though funding and timelines remain uncertain.