Quirks & Quarks

Waves are getting stronger and more dangerous thanks to climate change

The warming of the upper ocean water has an influence on the strength of winds, which in turn creates dangerously powerful waves.

Warming water means stronger winds which means bigger waves

Ocean waves like these ones hitting a breakwater in France are becoming more powerful as the surface water warms. (Christian Ferrer Creative Commons Attribution-Share 4.0)

As our planet continues to warm, scientists are kept busy trying to keep tabs on how climate change is impacting the Earth. Measuring sea level rise and the rate at which glaciers are melting are two of the more common areas of study. But scientists are using a new measuring stick: wave power. Although increasing energy in ocean waves is great for surfers, it's not so gnarly for anything living on the coast.

Climate change drops in

Climate change trends and projections are measured in the gang of usual suspects like rising sea levels, increasing global temperatures and decreasing sea ice. Now, analysis of the global marine climate has scientists looking at increases in wind speed and wave height as yet another indicator of climate change. This previously undetected signal of global warming is most prevalent in The Southern Oceans: the world's most energetic basins, the Indian Ocean and Pacific Ocean and the Atlantic Ocean. There is also a seasonality, as winter waves tend to be larger than the average.

Global wave power, which is the transport of the energy transferred from the wind into sea-surface motion, has increased globally by 0.4 per cent per year since 1948. (C. Lagattuta UCSC)

Making waves

The energy in ocean waves has been increasing over time as the upper ocean water has increased in temperature. Rising temperature of surface sea water influences global wind patterns. The changes in the ocean-atmospheric circulation result in stronger winds, which in turn mean higher and longer waves.

Using a variety of measuring techniques, including computer modelling and satellite images, Borja Reguero, a researcher in the Institute of Marine Sciences at the University of California Santa Cruz, has determined that wave power has increased globally by an average 0.4 per cent per year since 1948. Wave power has accelerated in the past two decades with a cumulative 2.3 per cent increase, per year, since 1994. This is due specifically to the warming of surface ocean water. 

As more energetic waves reach shore, they cause greater erosion to coastlines (Jon Sullivan)

Surf's up

Because this effect has been building for several decades, there is no reason to believe that this average increase will not continue into the future. Sea level rise will magnify these effects by allowing more wave energy to reach shores.

This comes with huge implications for coastal cities, including ports and harbours, as well as small island countries. The effects of the increase in wave power are especially apparent during the most energetic storm seasons. For example the 2013-14 storm season in the North Atlantic that resulted in severe flooding across the U.K., France and Spain, as well as the 2017 devastating hurricane season across the Caribbean. 

A car passes through a flooded section of road in south-east England in 2013. (Ben Stansall/AFP/Getty Images)


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