Over the past four decades, a discernible increase in global wave energy has been observed, as reported in a recent study published in the journal Nature Communications. This phenomenon is closely linked to the heightened storminess associated with rising global temperatures. The study utilized data from global seismographic networks, which are traditionally employed for monitoring earthquakes but also capture seismic signals originating from natural elements such as wind, water, and human activities.
The most notable of these signals is the global microseism—a constant thrum generated by storm-driven ocean waves. Two primary types of seismic signals, known as secondary and primary microseisms, are attributed to ocean wave activity. The former, with a period between eight and 14 seconds, results from the interference of waves traveling in different directions. The latter, characterized by a steady hum with a period between 14 and 20 seconds, is caused by the direct pushing and pulling of the seafloor by traveling ocean waves, particularly in regions with water depths less than 1,000 feet.
The study focused on estimating and analyzing historical primary microseism intensity at 52 seismograph sites worldwide with long-standing records. Of these sites, 41 (79 percent) exhibited significant and progressive increases in energy over the decades. The findings suggest a median annual increase in globally averaged ocean wave energy of 0.27 percent since the late 20th century, rising to 0.35 percent per year since 2000.
Notably, the Southern Ocean near the Antarctica peninsula exhibited the highest overall microseism energy, emphasizing the stormy nature of this region. However, the study highlighted that North Atlantic waves have experienced the fastest intensification compared to historical levels in recent decades, aligning with research indicating increased storm intensity and coastal hazards in this area. Noteworthy examples, such as Storm Ciarán in November 2023, underscore the growing impact of these intensified waves.
With oceans absorbing approximately 90 percent of the excess heat from rising greenhouse gas emissions, the resultant increase in wave heights poses a significant threat to coastal infrastructure. This threat is exacerbated by ongoing sea level rise and subsidence, emphasizing the urgency of mitigating climate change and incorporating resilience strategies into coastal development and environmental protection initiatives.