\n<\/p>\n
SEATTLE — <\/span>Sea levels along the West Coast will begin to rise by up to a foot this month as a series of pulses of warm water called Kelvin waves hit the shoreline and move north, sparking concerns about beach erosion and flooding in areas already impacted by climate change<\/a> and El Ni\u00f1o.<\/p>\n Kelvin waves are not like tsunamis, and they don’t curl over and crash on the beach. A better image is water sloshing in the bathtub or a swimming pool during an earthquake. In the ocean, they are bulges of water that lift the sea level as they move along the coast. They’re common during El Ni\u00f1o events, but this year\u2019s super El Ni\u00f1o<\/a> could intensify the impacts, experts say.<\/p>\n Over the next week, the 6-inch to foot-tall surge will move north along the California coast at about 6 miles per hour (9.6 kilometers per hour), or 150 miles per day (241 kilometers per day), bringing higher sea levels to Oregon and Washington state. Experts predict the waves will continue to pass through from October until February. <\/p>\n \u201cIt\u2019s not that this Kelvin wave is going to come and flood anything on its own,\u201d said Michael Jacox, a research oceanographer with National Oceanic and Atmospheric Administration Fisheries\u2019 Ecosystem Science Division. <\/p>\n Instead, it raises the baseline.<\/p>\n If you start with sea levels that are 6 inches higher than normal, when you have really high tides, big storms or storm surges, the water levels are now 6 inches higher, he said. \u201cThe effects can be amplified,\u201d he said.<\/p>\n The waves also increase ocean temperatures and push cold, nutrient-rich waters deeper below the surface, which has an impact on marine life. <\/p>\n Here’s what to know about Kelvin waves.<\/p>\n Kelvin waves are a \u201cfact of life\u201d during an El Ni\u00f1o<\/a>, a naturally occurring climate pattern involving the warming ocean waters<\/a>, said Dillon Amaya, an assistant professor in the Department of Marine, Earth, and Atmospheric Sciences at North Carolina State University.<\/p>\n They form when the trade winds along the equator change direction. <\/p>\n Winds blowing east to west along the equator push water in the Pacific Ocean west toward Asia, Jacox said. When those winds weaken or reverse direction, that bulge of water gets pushed back toward the east along the equator until it hits South America.<\/p>\n When the surge of water hits the coastline at the equator, it moves north and south along the North and South American coasts. <\/p>\n The wave isn’t visible to the naked eye and they won’t cause boats to go up and down, Amaya said. It’s more like a big pancake. It’s wider than it’s deep: The bulge extends 12 to 20 miles (19 to 32 kilometers) off the coast and about 200 meters deep, Amaya said. <\/p>\n Many coastal communities are already grappling with the impacts of rising sea levels, like the coastal erosion eating away at the beach in San Clemente,<\/a> California. Waves are also getting bigger<\/a>, experts say.<\/p>\n The higher sea levels could exacerbate those problems.<\/p>\n \u201cPeople are on edge,\u201d Amaya said. \u201cThey think about more flooding happening, more beach erosion so when you hear elevated sea states coastal inundation risk, I think that raises a lot of anxiety.\u201d<\/p>\n The higher sea level combined with larger than average waves from North Pacific swell, which are expected during the El Ni\u00f1o<\/a>, plus large spring tides from October to February, can cause exceptional erosion on the West Coast, said Sean Vitousek, a research oceanographer with the U.S. Geological Survey. <\/p>\n Generally, the largest El Ni\u00f1o<\/a> events of 1982-83, 1997-98 and 2015-16 caused West Coast beaches to experience their worst erosion on record, Vitousek said. <\/p>\n \u201cThe loss of protective beaches also increases wave impacts and coastal flooding on property and infrastructure,\u201d he said.<\/p>\n Things could intensify over time as more waves arrive over the winter.<\/p>\n Typically El Ni\u00f1os are associated with five or six of these waves, Amaya said. During the last major El Ni\u00f1o in 2015-2016 there were five Kelvin waves.<\/p>\n One already came through in May or June and there\u2019s evidence of a third Kelvin wave forming, he said. Experts expect it to continue up the coast over the next month or so.<\/p>\n There’s concern the waves could worsen challenges along the Southern California coast, said Alyssa Napuri, deputy chief of staff for Orange County Supervisor Katrina Foley. Already, waves are approaching a seaside rail line and oceanfront homes were damaged during swells last month tied to Hurricane Marie<\/a>.<\/p>\n Authorities are placing emergency sand on beaches as quickly as possible, Napuri said, adding that forecasts show the Kelvin Wave could send water levels between six to 12 inches higher. <\/p>\n \u201cWe\u2019re already struggling as it is,\u201d Napuri said.<\/p>\n California Gov. Gavin Newsom, a Democrat, proclaimed a state of emergency in late September to prepare the state for what will likely be a historic El Ni\u00f1o season. The proclamation will help the state \u201cmove faster to protect communities, stage critical resources, and strengthen readiness before severe weather intensifies,\u201d the governor said in a statement. <\/p>\n Experts with the Washington state Department of Natural Resources are ready to respond to any disasters that might come with the Kelvin waves, said spokesperson Courtney James. They regularly coordinate through the state Emergency Management Division but they have not been asked to do any special preparation so far, she said. <\/p>\n Actual damages from the Kelvin waves will depend on the storms and tides magnified by El Ni\u00f1o, and if they’re stronger, the damage could be significant, Amaya said. <\/p>\n \u201cIt\u2019s too too early to be sure whether this particular winter season will be a record breaker in terms of this El Ni\u00f1o, but this El Ni\u00f1o itself is certainly on that trajectory of being one of the largest if not the largest El Ni\u00f1o we\u2019ve ever seen,” he said. <\/p>\n __<\/p>\n Associated Press reporter Amy Taxin contributed to this story from Santa Ana, California. <\/p>\n<\/div>\n