El Niño-driven Kelvin wave set to raise California sea level by up to six inches

A coastally trapped Kelvin wave, driven by the intensifying El Niño, is traveling up Mexico’s shoreline and is forecast to arrive on the California coast in early October, raising sea levels by roughly six inches for an extended period. Experts warn that even this modest increase could exacerbate the already significant erosion and flooding that have damaged properties in Long Beach, Malibu and Dana Point after recent high-tide storms.

The wave follows a pattern where warm Pacific waters shift eastward, a hallmark of El Niño, and will travel from the Gulf of California to San Diego, then Los Angeles and San Francisco. Scientists stress that the wave adds to a foot of sea-level rise observed over the past century from global warming, as well as to ongoing marine heatwaves that threaten marine ecosystems. NOAA’s Climate Prediction Center estimates a 95% chance of a “super” El Niño this year, which could also boost late-season Pacific hurricanes, further threatening the West Coast.