A 2010 surf competition at Mavericks Beach in California. Shalom Jacobovitz via Wikipedia
Thanks to intensifying storms in the North Pacific, winter waves along the California coast have grown around a foot taller over the last half-century, new research shows.
When waves rebounding off the shore collide with incoming waves, the impact sends a ripple of energy through the seafloor that can be picked up by seismographs on land. The taller the waves, the bigger the collision, the greater the seismic signal. To track the changing height of waves in California, Peter Bromirski, an oceanographer at UC San Diego, scoured seismic records dating back to 1931.
He found that, since 1970, winter waves have grown by nearly a foot (0.3 meters) along the California coast. “The fact that this change coincides with the acceleration of global warming near 1970 is consistent with increased storm activity over the North Pacific resulting from climate change,” he said in a statement.
Bromirski also found that from 1996 to 2016, California saw twice as many storms with waves over 13 feet (4 meters), as compared with storms in the mid-20th century. The findings, published in the Journal of Geophysical Research Oceans, follow on other research showing that waves are growing taller in the North Atlantic.
Bigger waves threaten to worsen the impact of rising seas, Bromirski said. “Waves ride on top of the sea level, which is rising due to climate change,” he said. “When sea levels are elevated even further during storms, more wave energy can potentially reach vulnerable sea cliffs, flood low-lying regions, or damage coastal infrastructure.”
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