A long time ago, in 2017, I wrote a short fiction story called This Is the Dystopian Future of Surf. It was set in the future, where wave pools were everywhere and the ocean was too toxic to surf. Storms had gotten so violent that entering the ocean was basically a death sentence. “The storms got bigger and bigger as the ocean warmed and messed with the currents, great swathes of cold ramming into greater swathes of warm, throwing off the delicate equilibrium that controls the planet’s weather,” I wrote. “At some point, the storms got too violent, the waves too big. For surfers, everything was great until it was terrible.” Well, a new study examining the effects of global warming on the ocean might be an indicator that I might not have been too far off.
The study, published in the journal Nature, is called “Increasing Ocean Wave Energy Observed in Earth’s Seismic Wavefield Since the Late 20th Century.” In short, it looks at how the force of ocean waves interacts with the sea floor.
“As oceans waves rise and fall, they apply forces to the sea floor below and generate seismic waves,” wrote Richard Aster, Professor of Geophysics and Department Head at Colorado State University. “These seismic waves are so powerful and widespread that they show up as a steady thrum on seismographs, the same instruments used to monitor and study earthquakes. That wave signal has been getting more intense in recent decades, reflecting increasingly stormy seas and higher ocean swell.”
The study is, as you’ve likely guessed, not focussed entirely on how much bigger the waves are getting. It’s more about how the increasing size of the waves is showing up on seismographs. Using global data including ocean, satellite and regional seismic studies, the study’s authors found a “decades-long increase in wave energy that coincides with increasing storminess attributed to rising global temperatures.”
Those seismographs are incredibly sensitive. They pick up on movement caused by volcanic eruptions, nuclear and other explosions, meteor strikes, landslides, glacier-quakes, and even wind and water activity. One interesting aside here: when the world went into lockdown during the pandemic, it became much, much quieter. Of all the things a seismograph picks up, the thing that is basically a constant is “the incessant thrum created by storm-driven ocean waves.” And that thrum is getting much louder.
The researchers used data from the late 1980s at 52 seismograph sites around the world. Looking at those same sites now, they found that 79 percent of them showed “highly significant and progressive increases in energy over the decades.”
According to the paper, the global average ocean wave energy has increased about 0.27 percent each year since the late 20th century. After 2000, however, that number jumped up to 0.35 percent per year.
“We found the greatest overall microseism energy in the very stormy Southern Ocean regions near the Antarctica peninsula,” the authors wrote. “But these results show that North Atlantic waves have intensified the fastest in recent decades compared to historical levels. That is consistent with recent research suggesting North Atlantic storm intensity and coastal hazards are increasing. Storm Ciarán, which hit Europe with powerful waves and hurricane-force winds in November 2023, was one record-breaking example.”
The research also looked at the winter storms between the two hemispheres, how the shrinking Antarctic sea ice can have a dampening effect on them, and the multi-year highs and lows associated with El Niño and La Niña cycles and their long-range effects on ocean waves and storms.
“Together,” Aster wrote in an article about the study in The Conversation, “these and other recent seismic studies complement the results from climate and ocean research showing that storms, and waves, are intensifying as the climate warms.”