Massive Kelvin wave threatens to raise California sea levels by up to a foot

Scientists say a Kelvin wave, a type of coastal trapped wave linked to El Niño, is moving toward the California coastline and could raise water levels by up to a foot. The bulge will span roughly 12 to 18 miles offshore, compounding existing threats from high tides and storm surge. Oceanographer Dillon Amaya notes that each two-to-four-inch rise in baseline sea level roughly doubles flood risk.

Mark Merrifield adds that the combination of this wave, elevated sea temperatures, and ongoing beach erosion may produce the highest sea levels ever recorded in the state. Recent incidents, such as waves overtopping Pacific Coast Highway in Malibu, illustrate the growing vulnerability of coastal communities. The wave also suppresses the upwelling of cold water, reinforcing the warm surface conditions typical of El Niño.