A massive underwater wave linked to this year’s El Niño weather phenomenon is progressing along the western coast of the Americas, prompting concerns from scientists regarding how climate change is amplifying the effects of this natural occurrence.
Known as the Kelvin wave, this event is not surprising. However, it is occurring against the backdrop of human-induced climate change, which has already heated the oceans and atmosphere. A smaller wave reached British Columbia earlier this summer, and another one is anticipated to arrive within the next one to two weeks, as confirmed by Bill Merryfield, a research scientist at Environment and Climate Change Canada.
The Kelvin wave is a naturally occurring weather event, similar to El Niño itself. During normal years, winds blow from east to west along the Pacific Ocean’s equator, pushing water from South America towards Asia. However, during El Niño periods, these east-to-west winds weaken or reverse direction, enabling water to move eastward.
As these Kelvin waves hit the South American coast, the water accumulation splits and flows up and down the Americas’ coasts, eventually reaching Canada. Sea-level observations from Tofino on Vancouver Island’s Pacific coast illustrate the impact of the earlier Kelvin wave in June.
Rather than a colossal tsunami-like wave, the Kelvin wave causes a temporary rise in sea levels, creating a broad but shallow bulge in the ocean surface by approximately a foot. This effect was explained by University of California climate scientist Daniel Swain.
The consequences of the Kelvin wave are most noticeable during king tides, especially high tides resulting from the combined gravitational forces of the sun and moon. When this sea level rise is added to a king tide, along with potential winter storms causing storm surges, the situation can become critical, Merryfield highlighted.
These compounded effects of the Kelvin wave, intensified northward winds, winter storms, climate change-induced sea level rise, and extreme weather patterns could exacerbate coastal flooding and erosion. Previous strong El Niños have caused widespread erosion on California beaches, prompting emergency sand placement by local authorities to counter the expected six to 12-inch water level rise due to the Kelvin wave.
Merryfield cautioned that the impacts of the Kelvin wave and El Niño could extend beyond the current season. During El Niños, some of the ocean’s stored heat, which mitigates global warming from greenhouse gases, is released into the atmosphere. Consequently, 2027 is anticipated to become the warmest year on record by a significant margin, according to Merryfield and other climate research organizations and scientists.