A massive underwater wave linked to this year’s El Niño weather phenomenon is making its way up the western coast of the Americas, sparking concerns among scientists over how climate change is amplifying the effects of this natural event.
Known as the Kelvin wave, this occurrence is not unexpected. However, it is occurring against the backdrop of human-induced climate change, which has already heated up the oceans and atmosphere.
A smaller wave had already reached British Columbia earlier this summer, with another wave anticipated to arrive within the next one to two weeks, as reported by Bill Merryfield, a research scientist at Environment and Climate Change Canada.
The Kelvin wave is a naturally occurring weather pattern, much like El Niño itself. In regular years, winds travel from east to west along the equator in the Pacific Ocean, pushing water from South America towards Asia.
During El Niño years, these east-to-west winds weaken or reverse direction, allowing water to move eastward instead. When the Kelvin waves hit the South American coast, the water accumulation splits and begins moving up and down the Americas’ coasts, eventually reaching Canada.
Data from sea-level monitoring at Tofino on Vancouver Island’s Pacific coast illustrates the impact of the earlier Kelvin wave in June. Rather than a tsunami-like wave, the Kelvin wave causes a temporary rise in sea levels.
According to University of California climate scientist Daniel Swain, the Kelvin wave creates a broad, shallow bulge in the ocean’s surface, increasing the height by about a foot over a wide area.
Merryfield highlighted that the effects are most noticeable during king tides, especially high tides when the gravitational forces of the sun and moon combine to produce higher-than-normal tides. When combined with a sea level rise of 30 centimeters due to El Niño, along with potential winter storms causing storm surges, the situation can become critical.
El Niño can enhance northward winds along the coast, pushing more water toward the shore, intensifying surges. These combined impacts, including the Kelvin wave, stronger northward winds, winter storms, and the influence of climate change on sea levels and extreme weather, may exacerbate flooding and erosion along the coast. Past strong El Niños have led to extensive erosion on California’s beaches.
Authorities in California are taking preventive measures by placing emergency sand on beaches, expecting the Kelvin wave to raise water levels by six to twelve inches, according to the Associated Press.
Merryfield cautioned that the effects of the Kelvin wave and El Niño could extend beyond the current season. While oceans absorb excess heat due to greenhouse gases, mitigating global warming, El Niños release some of this stored heat into the atmosphere. As a result, 2027 is likely to be the warmest year on record by a significant margin, according to Merryfield and other climate research organizations and scientists.