California’s coastal communities are gearing up for the potential impact of rising sea levels as the El Niño phenomenon strengthens. New data suggests that in the coming weeks, coastline areas might experience increased sand erosion and damage due to these changes.
A noteworthy phenomenon tied to El Niño, a “coastally trapped Kelvin wave,” is making its way up the coast of Mexico, expected to reach the U.S. West Coast soon. While this wave won’t create surfable conditions and may go unnoticed by swimmers and boaters, it is projected to elevate sea levels along the California coast by approximately six inches. This rise could have lasting effects over several months, according to Dillon Amaya, a marine expert at North Carolina State University.
Recent Coastal Challenges
This recent addition of six inches might not seem significant, yet it poses a serious threat to a coastline already grappling with environmental stress. Recent strong surf has resulted in considerable damage, including a severe sinkhole at a celebrity’s Malibu residence and erosion impacting homes in Dana Point. “We’ve seen how crucial these factors are, especially during high tides and hurricane-generated swells that have viciously battered Southern California homes, particularly at the peak of tidal cycles,” noted Jonathan Warrick, a research geologist with the U.S. Geological Survey.
Over the past 125 years, California has witnessed roughly one foot of sea level rise, largely attributed to human-induced climate change and polar ice melt. The California coast is also experiencing higher-than-usual tides, along with the challenges posed by ongoing marine heat waves.
Amaya elaborates, “The combination of the Kelvin wave, El Niño effects, and marine heat waves is contributing to an additional foot of sea level rise—compounding the challenges we already face due to climate change.” Further, recent marine activity has triggered concerns about mass strandings on California’s beaches.
Understanding the Kelvin Waves
Though Kelvin waves were previously an obscure concept, they play a pivotal role in the El Niño pattern—a climate sequence marked by warmer ocean waters in the central and eastern equatorial Pacific, fundamentally affecting global weather systems. During El Niño, the typical east-to-west trade winds weaken or reverse, leading to the eastward movement of hot water typical of regions like Indonesia.
As these waves head towards California, they can raise sea levels by between six and twelve inches, prolonging this elevated state for months. This increase in water levels, particularly when coupled with storm systems, heightens the risk of flooding and beach erosion.
Currently, the coastally trapped Kelvin wave is positioned off Mexico’s west coast, expected to transition into the Gulf of California on or about September 19. Following this, it will take approximately 18 days to reach Southern California, leading to anticipated impacts by early October.
With conditions developing for a “super” El Niño, there is a burgeoning likelihood of wetter and potentially disruptive weather patterns ahead. Forecasters indicate a 75% probability that this El Niño will surpass all prior events since 1950, with a staggering 98% chance of being classified as “very strong” by December.
The sea beneath is experiencing unprecedented warm temperatures exceeding 18 degrees, leading to rising concerns over the coastal areas’ future. The Kelvin wave’s arrival is redundant of earlier waves documented this season, alongside issues like harmful algal blooms affecting marine ecosystems.
Historically, strong El Niño events have triggered a barrage of Kelvin waves, with the last major occurrence in 2015-16 resulting in record erosion along the California coast. Additionally, the ongoing hurricane season in the eastern Pacific could propagate more extensive risks for California, as El Niño stimulates hurricane activity.
As conditions evolve, the potential for impactful storms — such as the formation of new tropical systems — remains a pressing concern for California in the coming months, emphasizing the importance of monitoring these oceanic changes closely.
