For example, defences may be designed to cope with a 100-year wave event.Įxtreme ocean waves generated by strong surface winds can reach heights of over 20 meters at the high latitudes of the globe – that’s as high as four double-decker buses stacked on top of each other.īut the surface winds that drive wave heights are in turn driven by the climate system, and so are subject to climate change.
Like extreme floods, extreme waves are classified by the frequency with which they tend to occur, and this frequency drives the design requirements for ocean structures or coastal defences. Australia's mountains are still growingĪt a time when 290 million people already live below the 100-year flood level (that is, they live below levels where there is at least a one per cent probability of flooding every year), an increase in the risk of extreme wave events may be catastrophic, as larger and more frequent storms will cause more flooding and coastline erosion.Įxtremes are defined as unexpected, unusual and sometimes unseasonal events. This may not sound like a big increase, but it means that almost 60 per cent of the world’s coastline will experience larger and more frequent extreme waves.
Our new research suggests that by the end of the century the magnitude of extreme wave events will have increased by up to 10 per cent over extensive ocean regions, and the frequency of storms that generate extreme waves will have increased by five to 10 per year. Rising sea levels as the climate warms are a threat to our coastlines, but climate change is also driving more extreme waves that will also increase flood risks. These waves increase coastal erosion and the risk of flooding.
What many don’t realise is that at the same time as sea levels are rising, storms are increasing in magnitude and frequency, resulting in larger ocean waves. When most of us think about what climate change will do to our coastlines we tend to focus on how sea-levels are rising as the polar ice caps melt and the oceans warm.
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