A massive underwater wave linked to the current El Niño weather event is making its way up the western coasts of the Americas, prompting concerns among scientists about how climate change is amplifying the effects of this natural occurrence.
Known as the Kelvin wave, this phenomenon is not unexpected but is occurring against the backdrop of human-induced climate change, which has already warmed the oceans and atmosphere. A previous smaller wave reached British Columbia earlier this summer, and another wave is anticipated to arrive in the next one to two weeks, as per Bill Merryfield, a research scientist at Environment and Climate Change Canada.
The Kelvin wave, like El Niño itself, is a natural weather event. In typical years, winds blow from east to west along the equator in the Pacific Ocean, pushing water from South America towards Asia. During El Niño years, these winds weaken or change direction, allowing water to move east instead. When these Kelvin waves hit the South American coast, they split and move up and down the Americas’ coasts, eventually reaching Canada.
Data from sea-level monitoring at Tofino on Vancouver Island’s Pacific coast demonstrates the impact of the earlier Kelvin wave in June. Rather than creating a tsunami-like wave, the Kelvin wave temporarily elevates sea levels, creating a broad, shallow bulge in the ocean surface.
Merryfield highlighted that the most significant impacts occur during king tides, especially high tides resulting from the combined gravitational pull of the sun and moon. When coupled with a 30-centimeter rise in sea levels due to the Kelvin wave and potential storm surges from winter storms, the consequences can be severe.
The compounding effects of the Kelvin wave, stronger northward winds, and winter storms, combined with climate change-induced sea level rise and extreme weather intensification, may exacerbate flooding and erosion along the coasts. Past strong El Niños have caused widespread erosion on California’s beaches, prompting emergency sand placement efforts and expectations of a six to 12-inch water level increase.
Merryfield cautioned that the impacts of the Kelvin wave and El Niño could extend beyond the current season. As greenhouse gases trap excess heat, the oceans absorb much of it, moderating global warming. However, during El Niños, some of this stored heat is released into the atmosphere, potentially leading to 2027 becoming the warmest year on record.
The consequences of the Kelvin wave and El Niño may have far-reaching effects, as stated by Merryfield and echoed by various climate organizations and scientists.
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