There’s no shortage of ways climate change will impact the world as we know it today. On the surface, plenty of California surfers would probably be happy to hear that the global phenomenon is believed to lead directly to bigger waves along the coast. But according to a researcher from the Scripps Institution of Oceanography, whose research makes that direct correlation, it’s actually bad news for the Golden State.
UC San Diego Scripps Institution of Oceanography researcher emeritus Peter Bromirski’s research was published in the Journal of Geophysical Research Tuesday, which relied on nearly a century of seismic records to determine whether or not wave heights have been changing over time along the coast. And how seismic data correlates to breaking waves in the ocean? It turns out that specific wave height data isn’t something that goes back very far so Bromirski had to improvise. According to a press release from the Institution, the refraction of wave energy off the shore and directly into new oncoming waves can be recorded as seismic energy at the seafloor. Seismographs stationed inland record that same energy, which directly relates to wave height. Bromirski used this exact data as the most reliable, comprehensive record of wave heights dating back to 1930 because, well, there was no other direct measurement of waves dating back that far. It’s a method he actually developed in the 1990s and in 1999, he published a paper detailing it all.
What’d he find?
“In the era beginning after 1970, California’s average winter wave height has increased by 13 percent or about 0.3 meters (one foot) compared to average winter wave height between 1931 and 1969,” the research concluded. Bromirski also found that in the 20 years between 1996 and 2016, California saw nearly twice as many storm events producing waves larger than 13 feet compared to the two decades spanning 1949 to 1969.
“After 1970, there is a consistently higher rate of large wave events,” Bromirski says. “It’s not uncommon to have a winter with high wave activity, but those winters occurred less frequently prior to 1970. Now, there are few winters with particularly low wave activity. And 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.”
The findings of this study mirror the findings of a similar research project in 2000. That study observed changing wave sizes and storm activity in the Northeast Atlantic Ocean.
“For the period 1954–77, we detect an average of seven days per month with strong microseismic activity, without a significant trend,” they said. “This number increases significantly in the second half of the record, reaching approximately 14 days of strong microseisms per month. The implied increase in northeast Atlantic wave height over the past 20 years parallels increased surface air temperatures11 and storminess12 in this region, suggesting a common forcing.”
It all sounds great from a surfing standpoint, obviously. But Bromirski warns that this trend spells bad news for coastal communities.
“Waves ride on top of the sea level, which is rising due to climate change,” said Bromirski. “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.”
