A new study published in the journal Nature Communications has revealed an as-yet-unseen consequence of climate change, wherein the energy of ocean waves have been increasing around the world caused by widespread ocean warming, which could potentially create further repercussions from coastal change and flooding, and the larger threat of sea level rise.
Published on January 14 in Nature Communications, the new study — “A recent increase in global wave power as a consequence of oceanic warming” — shows that global wave power (the transport of energy transferred from the wind into sea-surface motion) has increased around the world by 0.4% per year since 1948. The study also showed long-term correlations and statistical dependency with sea surface temperatures — both globally and by ocean sub-basins — and particularly between the tropical Atlantic temperatures and the wave power in high-south latitudes, already the most energetic region globally.
The results of the study show that upper-ocean warming — warming which is a direct consequence of anthropogenic global warming, as man’s excess warming is sunk into the ocean — is making waves stronger and identifies wave power as a potentially valuable, albeit unknown until now, climate change indicator.
The study focused on the energy which is contained in ocean waves — energy which is transmitted from the wind and transformed into wave motion, also known as wave power, and which has been increasing in direct association with historical warming of the ocean surface. This rising trend in sea surface temperatures is not news, and has been seen to be influencing wind patterns globally, but the new study shows that ocean waves have also been getting stronger.
“For the first time, we have identified a global signal of the effect of global warming in wave climate,” said lead author Borja G. Reguero, a researcher in the Institute of Marine Sciences at the University of California, Santa Cruz. “In fact, wave power has increased globally by 0.4% per year since 1948, and this increase is correlated with the increasing sea-surface temperatures, both globally and by ocean regions.”
This is just one of the many impacts that climate change is having upon the planet’s oceans and which have been observed for decades, if not longer. Climate change has changed ocean-atmosphere circulation and water warming, and changing wave power is only the next observable change that man-made global warming is having.
“This study shows that the global wave power can be a potentially valuable indicator of global warming, similarly to carbon dioxide concentration, the global sea level rise, or the global surface atmospheric temperature,” explained coauthor Inigo J. Losada, director of research at the Environmental Hydraulics Institute at the University of Cantabria (IHCantabria), where the study was developed.
Specifically, the study’s data shows that wave power has increased globally by 0.47% per year between 1948 to 2008, and by 2.3% per year since 1994. By ocean, the Southern Ocean has changed the most since 1948, by 0.58% per year, the Pacific has increased by 0.35% per year, and the Atlantic and Indian Oceans by 0.26% per year.
While alternatively impressive and distressing, these results are not just abstract changes but will have specific real-world implications for coastal cities and communities around the world.
City and community planners already need to understand and take into account the energy of ocean waves so as to properly build infrastructure — from ports and harbors, seaside residential dwelling, or breakwaters and levees. Further, wave action is one of the main drivers of coastal change and flooding and, unsurprisingly, as wave energy increases the resulting effects can be tremendous. To make matters worse, sea level rise — which is already well underway and observable around the globe — will further aggravate the negative effects of the increased energy of ocean waves by allowing more wave energy to reach shoreward.
The study reveals a long-term trend of increasing wave energy which will need to be addressed and understood and which will have significant implications for coastal communities, but the study also revealed that the increase of wave power are particularly apparent during the most energetic storm seasons — such as that which occurred during the winter of 2013-14 in the North Atlantic and which impacted the west coast of Europe, or the 2017 hurricane season in the Caribbean which devastated so many of the island nations in the region.
“Our results indicate that risk analysis neglecting the changes in wave power and having sea level rise as the only driver may underestimate the consequences of climate change and result in insufficient or maladaptation,” explained coauthor Fernando J. Méndez, associate professor at Universidad de Cantabria.
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