El Niño to raise California coastal sea levels by about a foot this fall
SALINAS, Calif. —
El Niño is expected to raise sea levels along California’s coast by about a foot this fall, driven by a massive Kelvin wave moving across the Pacific Ocean.
During El Niño, ocean temperatures in the eastern Pacific warm, causing atmospheric pressure to drop and sea levels to rise along the West Coast.
Warmer water and higher sea levels typically found in the western Pacific begin moving eastward across the ocean in the form of a wave. This Kelvin wave is a massive phenomenon that takes months to travel across the Pacific.
Over the past three months—June, July and August—warmer water and higher sea levels, represented in red, shifted eastward across the equatorial Pacific.
When the wave reaches the eastern edge of the Pacific, the water spreads poleward, including toward the West Coast.
As a result, high tides could be even higher, while storm surges could push water farther inland, increasing flood risks along the West Coast during the winter.
El Niño can produce more than one Kelvin wave. During the last strong El Niño, in 2015 and 2016, more than one wave developed, meaning water levels could rise again in the months ahead.