A massive underwater wave linked to this year’s El Niño weather phenomenon is advancing along the west coast of the Americas, raising concerns among scientists regarding how climate change is amplifying the effects of this naturally occurring event.
The so-called Kelvin wave is not a surprise. However, similar to El Niño itself, it occurs against the backdrop of anthropogenic climate change that has already elevated ocean and atmospheric temperatures.
An earlier, smaller wave reached British Columbia earlier in the summer, and experts predict the next one will arrive within one to two weeks, as stated by Bill Merryfield, a research scientist at Environment and Climate Change Canada.
“We previously observed a rise of over 30 centimeters in some areas in June. The upcoming wave is expected to be even more powerful,” Merryfield noted.
What triggers it?
The Kelvin wave is a naturally occurring weather event, akin to El Niño itself. In typical years, winds blow from east to west across the equatorial region of the Pacific Ocean, generally pushing water from South America toward Asia.
However, during El Niño years, those east-to-west winds may weaken or even reverse, allowing water to flow eastward instead.
“When these Kelvin waves reach South America’s coast, there’s no further east for this accumulation of water to go. Thus, it splits and begins to flow both north and south along the Americas’ coastlines,” Merryfield explained.
Data from sea-level monitoring at Tofino, located on Vancouver Island’s Pacific shore, illustrates the effects of the earlier Kelvin wave from June.
Unlike a massive tsunami, the Kelvin wave temporarily increases sea levels.
“You can visualize it as a broad, hundreds of miles wide, yet very shallow swell in the ocean’s surface elevation, perhaps by a foot or so,” remarked University of California climate scientist Daniel Swain in an interview with CBS News last month.
What effects will it have on the West Coast?
Merryfield indicated that the effects are most significant during king tides, which are particularly high tides resulting from the combined gravitational influence of the sun and moon that lead to above-normal tides.
“If you add that 30 centimeters of sea level rise to a king tide, and then perhaps a winter storm comes along causing a storm surge, that’s when issues really begin,” he commented.
“This additional foot or so of elevation due to El Niño can have a substantial impact.”
The unprecedented global heat driven by this year’s potent El Niño may result in nearly half a million additional deaths globally by the end of February, according to a report that emphasizes the influence of climate change on extreme heat.
These surges could be exacerbated by another El Niño-related effect, further elevating sea levels along the British Columbia coastline. El Niño can enhance northward winds along the coast, pushing even more water onto land.
These interconnected effects—the Kelvin wave, intensified northward winds, and winter storms, alongside climate change that is already elevating sea levels and exacerbating extreme weather—may increase flooding and erosion along the coastline. Previous strong El Niños have led to considerable erosion on California’s beaches.
Local officials in California are currently placing emergency sand on beaches, anticipating that the Kelvin wave will elevate water levels by six to twelve inches, as reported by the Associated Press.
Exceptionally high king tides and powerful waves damaged protective sand and wooden berms in Long Beach, Calif. in June. (Justin Sullivan/Getty Images)
The consequences of the Kelvin wave—and El Niño more generally—could have lasting effects beyond this season, Merryfield cautioned.
Oceans absorb a significant portion of the excess heat generated by greenhouse gases, helping to mitigate global warming as fossil fuels continue to be burned. However, during El Niño events, some of that stored heat is released from the seas into the atmosphere.
This is likely to make 2027 the hottest year on record “by a considerable margin,” Merryfield predicted, echoing similar alarms from various climate research organizations and scientists.
