Waves along California’s Central Coast are getting bigger as human-caused climate change warms the planet, according to a new study published this week in the Journal of Geophysical Research: Oceans.
Average winter wave height has increased by roughly one foot since 1970, the year that corresponds with global warming’s rapid acceleration, per the researchers.
And storms that produce waves measuring 13 feet high and taller have become more common, with twice as many of these events occurring between 1996 and 2016 as they did between 1949 and 1969, the researchers found. In recent years, those storms have occurred an average of 23 times each winter.
Taken together, the findings suggest that if average global temperatures continue to rise, California’s already threatened coast will be at an even greater risk of erosion and flooding as ocean water comes crashing in.
“It’s just one more indication that things are going in the wrong direction,” says Gary Griggs, an oceanographer at the University of California Santa Cruz who was not involved in the new research, to KSBW’s Ariana Jaso. “It’s like a giant chemistry experiment, only we can’t turn it off … waves are getting bigger, more powerful, the weather’s getting crazier. So that’s going to be more impact on the shoreline.”
To understand how waves have changed, study author Peter Bromirski, an oceanographer at the Scripps Institution of Oceanography, analyzed 90 years of seismic data captured between 1931 and 2021.
Scientists have only been making direct wave height measurements along the California coast since 1980, so looking at seismic data allowed Bromirski to go back much further in time. Seismic data can be used as a proxy for wave height, because when waves crash down and rebound off the coast, they collide with new, incoming waves, sending energy down into the ocean floor, where seismographs are recording. More energy equals taller waves.
He wasn’t surprised when the data showed taller waves and more intense storms, as that tracks with the effects of global warming.
“Warming puts more energy into the atmosphere, and you end up with stronger storms, which produce stronger winds and higher waves,” he tells the San Diego Union-Tribune’s Gary Robbins.
California’s coastline is already vulnerable to sea-level rise, erosion, stormy weather and other effects of climate change. Cliffs and even roadways have collapsed because of erosion and mudslides, which creates dangerous and, at times, deadly situations.
Average sea levels have risen roughly eight inches along the Golden State’s coast over the last 100 years, per the California Coastal Commission.
And scientists say the situation is likely to get worse: By the year 2100, between 25 and 70 percent of California’s beaches may disappear completely due to erosion from rising sea levels. Property worth an estimated $8 billion to $10 billion could be underwater by the year 2050.
“Erosion, coastal flooding, damage to coastal infrastructure is… something that we’re seeing more frequently than in the past,” Bromirski tells the Associated Press’ Julie Watson. “And… combined with sea-level rise, bigger waves mean that is going to happen more often.”