‘Harbinger of Change: 13-Foot Waves Persist in California’

Studies reveal that as the planet warms, waves off California’s coast are becoming larger, with surf at least 13 feet tall becoming more common. This innovative research, conducted by oceanographer Peter Bromirski at the Scripps Institution of Oceanography, utilized seismic records dating back to 1931 to track the increase in wave height. By analyzing the energy ripple caused by waves colliding with each other and the shore, Bromirski was able to measure wave height changes over the past 90 years.

Previously, scientists relied on data collected by the National Oceanic and Atmospheric Administration’s network of buoys. However, this data only went back to 1980 along the California coast. To gather data dating back further, Bromirski enlisted a team of undergraduate students to analyze decades of winter seismic readings. This meticulous process involved digitizing paper records and took several years to complete. The analysis revealed that average winter wave heights have increased by as much as a foot since 1970, coinciding with the acceleration of global warming.

The research also uncovered a significant increase in swells at least 13 feet tall, occurring twice as often between 1996 and 2016 compared to the period of 1949 to 1969. Surprisingly, periods of exceptionally low wave heights were observed prior to 1970 but have not occurred since. Bromirski warns that the combination of sea level rise and larger waves will lead to more frequent erosion, coastal flooding, and damage to coastal infrastructure.

Published in the Journal of Geophysical Research: Oceans, this study adds to the growing evidence that climate change is causing significant shifts in the world’s oceans. Other research has shown that waves are not only becoming taller but also more powerful.

Already, we are witnessing the damaging effects of intense storms and massive surf. In California, severe storms and giant waves have caused bluffs to collapse, piers to be damaged, and parts of Highway 1 to flood. Gary Griggs, an oceanographer at UC Santa Cruz who was not involved in the research, emphasizes the urgency of responding to these changes, as hurricanes are becoming more intense and lasting longer, and now waves are increasing in power.

Overall, this research underscores the rapid warming of the Earth and the rising sea levels. The challenge we face is how to effectively respond to these changes. (Read more waves stories.)