Waves are getting bigger

 Pocket - Waves are ... 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.

This has frightening implications for coastlines and the coastal communities that bear the brunt of the ocean’s fury. But if harnessed effectively waves – and the energy they transmit – may also have a part to play in tackling the climate crisis.

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.

Waves can also be created by seismic events such as earthquakes and volcanic eruptions. The waves created by these events can be immense. In 1958 a landslide at the mouth of Lituya Bay in Alaska sent a wave estimated to be 150 metres high rolling into the narrow inlet; as it spilled inland it levelled trees more than 500 metres above sea level. But their destructive power usually has more to do with their extremely long wavelengths than their height: although the 2004 Boxing Day tsunami was only about 10 metres high when it reached Aceh, it was up to 600 kilometres long, meaning that like a huge tide it swept vast quantities of water long distances inland.