Strengthening El Niño May Trigger Record Sea Levels and Flooding Along California Coast

A strengthening El Niño is projected to generate the highest sea levels ever recorded along California’s coast, according to Mark Merrifield, director of the UC San Diego Scripps Institution’s Center for Climate Change Impacts and Adaptation. NASA imagery shows the eastern Pacific already half a foot above the reference state, and Merrifield expects sea levels to rise well beyond the normal seasonal cycle by fall and winter.

The combination of elevated tides, powerful waves and increased rainfall could lead to extensive coastal flooding, salt-water intrusion, and accelerated shoreline erosion, particularly in Southern California where recent storms have caused injuries and damage. Historical El Niño episodes have pushed beaches landward by roughly 30 meters, reducing natural buffers against storm surge. The warm ocean waters also intensify marine heat waves, raising concerns about domoic acid blooms that could affect the Dungeness crab fishery and pose health risks to humans and wildlife. Climate scientists, including Daniel Swain, note that current ocean temperatures in the eastern tropical Pacific exceed any previously recorded values, suggesting this could be one of the strongest El Niños on record.