A coastally trapped Kelvin wave is moving up the coast of Mexico and is expected to reach the U.S. West Coast soon, bringing about 6 inches of added sea level off California for months. Dillon Amaya said the wave would not look like a surfable swell, but it could still add water to already stressed beaches and homes.
Amaya, an assistant professor at North Carolina State University, said, "This isn’t a surfable wave, and it wouldn’t be overtly noticeable to swimmers or boaters either." He also said, "It might not sound like much, but another 6 inches of sea level rise could further bludgeon the already battered California coast, especially if combined with the effects from a storm."
California beach communities
Jonathan Warrick, a research geologist with the U.S. Geological Survey, said houses across Southern California were battered especially at high tides. He said, "We saw why that’s important recently, with houses across Southern California getting battered, especially at those high tides. We had hurricane-generated swells and high tides, and the combination was extremely damaging to these homes."
That recent damage came after strong surf across Southern California this weekend blasted through a seawall in Long Beach, caused a massive sinkhole at a celebrity’s Malibu home and damaged several Dana Point homes. California beach communities are expected to see rising sea levels in the coming weeks as El Niño continues to strengthen.
Dillon Amaya on sea level rise
Amaya said the wave, El Niño and the marine heat wave together are adding to the water level already seen from climate change. He said, "The combination of the wave and El Niño and marine heatwave, all of these factors are contributing essentially another foot of sea level rise — in addition to what we’ve experienced from climate change," and added that the effects could last months.
He said Kelvin waves sit at the heart of El Niño. As El Niño develops, trade winds along the equator weaken or reverse, letting hot water and high sea surface heights move east through the central and eastern equatorial Pacific. Warm water near Indonesia is pushed toward a normally cooler part of the Pacific near Peru, then a Kelvin wave splits after reaching South America and one part heads north toward California.
Southern California high tides
Warrick said the danger rises when extra water lines up with high tides. He said, "When the water level is extra high, a foot or more higher than we expect it to be, then it can really wreak havoc."
The added water from the Kelvin wave comes on top of about a foot of sea level rise California has experienced over the past 125 years from human-caused global warming and the melting of the polar ice caps. The coast has also been dealing with abnormally high tides lately and a long-lasting marine heat wave unrelated to El Niño.
What happens next is the Kelvin wave reaching the U.S. West Coast and adding to the elevated water already pressing on Southern California beaches and homes.
