California Coast Faces Foot-High Sea Level Rise from El Niño

By mid-October, sea levels along California's coast are projected to rise by approximately one foot, a direct consequence of the developing El Niño. This significant increase is attributed to a coastal Kelvin wave, a substantial volume of water being pushed northward from off the coasts of Mexico and Central America.

This wave is a clear indicator of El Niño's presence and its early impacts on the United States. While not visible to the naked eye, satellites detect this Kelvin wave as it moves parallel to the coast at about six miles per hour, raising ocean heights.

The elevated sea levels pose an increased risk for coastal flooding and amplify damage from storm surges, especially when combined with El Niño-influenced winter storms. Scientists note that even a slight increase in sea level, such as 2 to 4 inches, can double the flood risk for West Coast communities situated at or near sea level.

This El Niño-driven sea level rise adds to the long-term trend of rising sea levels caused by climate change. The hotter ocean waters associated with El Niño also contribute to expansion, further increasing water levels. The total anticipated rise, including the Kelvin wave, could be 10 to 14 inches higher than normal.