Powerful 'Kelvin wave' triggered by super El Niño threatens to raise sea levels off the California coast for months

A powerful Kelvin wave triggered by this year's super El Niño is on its way to California's coastline, potentially raising sea levels by up to a foot for months, researchers caution. Kelvin waves are ocean phenomena spanning thousands of miles, but those generated during El Niño years are abnormal, causing oscillations within the ocean and raising surface height.

These waves shift the boundary between warmer surface water and colder bottom layers, moving it up and down within about 330 feet. Internal Kelvin waves are triggered by changes in equatorial winds around the Pacific Ocean. When these waves form, they can be tracked and predict their arrival on the South American coast. From there, the wave splits into two branches that continue north and south for thousands of miles.

California is not the only area at risk; all countries and regions bordering the eastern Pacific Ocean are vulnerable. In California, the influence of the internal Kelvin wave will add to the effects of tides during storms, potentially raising tides by tens of centimeters or a foot. Coastal California residents are advised to prepare for extreme conditions, such as flooding, as storms coinciding with high tides are more likely to cause damage.