Waves are getting bigger. Is the world ready?

[cbabe]

https://www.theguardian.com/environment/2025/feb/22/waves-are-getting-bigger-is-the-world-ready

Waves are getting bigger. Is the world ready?

Southern Ocean waves are growing larger and faster, threatening coastlines. But some scientists think they could help turn the tide in the climate crisis

By James Bradley
Sat 22 Feb 2025 14.00 EST

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Waves are also a vital part of the ocean system, helping to control the rate at which the ocean absorbs both heat and carbon dioxide and shaping and sustaining coastlines. And as ocean temperatures rise and weather patterns shift, waves are changing, in some oceans growing bigger and more powerful, and fast.

The waves we see on the ocean’s surface are mostly wind waves. Because wind pressure is never uniform, it creates tiny fluctuations in the water’s surface. As the wind pushes against these fluctuations they grow, creating larger and larger surfaces and transferring more and more kinetic energy from the air into the ocean. As they move across the water’s surface these fluctuations interact and combine, first forming ripples, then, as they become more regular, longer and larger waves. Out on the open ocean, where powerful winds can blow on the water for hundreds or even thousands of kilometres without interruption, these eventually become the massive swells that crash on to shores in higher latitudes.

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Nor are the waves we see on the surface the only waves in the ocean. The ocean is stratified into distinct layers of different temperature and salinity, and just as waves form on the interface between the water and the air, the outflow of fresh water from rivers and glaciers or tidal forces can send waves rippling along the boundaries between these layers. Even the daily motion of the tides is really a huge wave created by the gravity of the moon and sun that rolls around the planet. These processes play an important part in ocean mixing, helping transport denser, cooler water from the ocean’s depths towards the surface and to transfer nutrients and carbon from the sunlit upper layers into deeper water.

Understanding how these various systems are affected by the changing climate is not easy. Dr Mark Hemer from the CSIRO says that “waves are essentially the product of the winds, which means they’re affected by changes in atmospheric circulation at the surface.” And as global heating increases the amount of energy in the atmosphere it generates higher winds and bigger storms, resulting in larger and more powerful waves.

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