Killer waves are more common than we thought – and could get worse

Rogue waves can grow up to 30 metres tall (Picture: Getty/Tetra )

Far out to sea, beyond the horizon, lie real sea monsters. Long thought to be a myth imagined by sailors, these killers have now been seen and studied in real life.

They are rogue waves.

Rearing out of the sea up to 30 metres high – taller than three London buses end-to-end – rogue waves have swallowed up dozens of ships, and damaged many more, some being lucky enough to limp back to port after an encounter.

Now it seems they may be even more common than previously thought, and scientists may know where they come from.

Dr Alessandro Toffoli, a professor in ocean engineering, says: ‘Rogue waves are giant colossi of the sea – twice as high as neighbouring waves – that appear seemingly out of nowhere. Stories of unimaginable mountains of water as tall as ten-storey buildings have populated maritime folklore and literature for centuries.’

Professor Toffoli and his team at the University of Melbourne have been studying these monsters, which are still something of a mystery.

Waves can appear ‘from nowhere’ (Picture: Getty)

‘Recent technology has allowed scientists to spot rogue waves out at sea, making legend become reality,’ he says, writing for The Conversation. ‘The first and most famous measurement was of the Draupner wave, a 25.6-metre monster recorded in the North Sea on January 1, 1995.

‘Despite observations, we still don’t know how often rogue waves occur, or if we can predict them. A record of a rogue wave doesn’t include specific features that distinguish the sea around it, so we can’t make comparisons or predict the conditions needed.’

To try to better understand how and why massive waves form, the team set sail on the South African icebreaker S.A. Agulhas-II to chase rogue waves across the Southern Ocean, ‘where mighty winds shape Earth’s fiercest waves’.

Previous thinking suggested that rogue waves were purely a result of statistics – most waves are of average height, but some will be much smaller and some, particularly when they cluster together, will be much bigger.

A rogue wave mystery

On April 10, a giant cluster of waves more than 25 metres high spanning 2,000 miles appeared off the coast of Africa. For 24 hours the waves raced through the ocean, before vanishing.

The freak Texas-sized phenomenon was picked up by meteorological app Ventusky, which allows users to observe weather patterns, winds and waves as they happen.

Online, the reason behind these monstrous waves was obvious – aliens.

Many argued the waves were caused by an alien craft, or ‘unidentified submersible object’ – USO.

Others joked it was the Kraken, a mythical giant squid that terrorises sailors, or a portal opened up following the April 8 solar eclipse.

Unfortunately, the mystery turned out to be much less out there. Not only were the waves not caused by aliens, they weren’t actually waves at all.

An error in the program that creates visualisations invented the 24-hour storm.

So really it was rogue software, not rogue waves.

However, lab experiments and theoretical models suggest there is more to rogue waves than simple stats, and that they could be more common than the maths would suggest.

By studying the Southern Ocean, a famously rough and violent sea, Professor Toffoli and his team found that ‘young’ waves were taller than old waves, reaching almost five metres, and that these were gaining energy from the wind. Younger waves were also steeper – not good for boats in their path – and were more likely to break, forming ‘white caps’.

The Southern Ocean (Picture: A Toffoli)

‘When waves go faster than wind, they stop being accelerated by it and reach a “mature” stage of full development,’ says Professor Toffoli.

‘Through this process, the wind creates a chaotic situation where waves of different dimensions and directions coexist.

‘Our recent observations show that unique sea conditions with rogue waves can arise during the “young” stage – when waves are particularly responsive to the wind.’

However, they also discovered that wind is not the only factor.

Climate change could increase the frequency and size of rogue waves (Picture: Getty/500px)

Every so often, one wave will ‘self-amplify’, by stealing energy from those around it. Studies suggest this could make rogue waves ten times more likely, but again, it was all theoretical.

But by measuring waves in real life, Professor Toffoli and his team found hungry young waves showed signs of self-amplification and an increased likelihood of turning rogue.

‘This mirrors what lab models have reported,’ he says. ‘Sea conditions theoretically more prone to self-amplification would produce more rogue waves.’

All of this not only means that rogue waves are much more common than previously thought, but could become even more powerful in the future as climate change leads to stronger winds – meaning younger, rogue-prone waves can absorb more energy.

No longer a myth, these sea monsters could pose a growing threat to sea travel, making it all the more important to be able to predict when they may appear.

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