Bigger waves will redraw coastlines around globe
Australia
It may seem like good news for surfers, but it’s bad news for everyone else. Australian scientists have warned that climate change will create larger and more powerful waves that will alter coastlines around the globe.
The researchers have found that about half of the world’s coastlines will be at risk from ‘‘wave climate change’’ by the final two decades of the century if greenhouse gas emissions in- crease at present rates.
Wind patterns would change in an altered climate, the study says, affecting the waves that surface winds generate. This may ‘‘exacerbate or even exceed in some coastal regions impacts of future sea level rise’’.
The study, led by scientists from Griffith University and published in the journal Nature
used about 150 simulations. They found that Australia and the west coast of South America would be among the worst-affected areas.
Damaging waves up to 6m tall are forecast to hit Sydney this week in what meteorologists have described as ‘‘quite a rare event’’.
Separate research published in the journal Science, which examined 33 years of wind and wave records from satellite measurements, found that global average wind speeds rose by 2.9 knots (5.3kmh) and wave height by an average of 30cm.
The Griffith study found that about 40 per cent of coastlines would experience ‘‘robust change’’ in at least two of three wave variables: height, period and direction.
Ocean regions can expect annual mean significant wave height – the average difference between trough to crest of the highest third of waves – to rise by between 5 and 15 per cent on the baseline recorded between 1979 and 2004.
In some regions, wave height will be the same but their length or frequency is forecast to change. This can result in more force exerted on the coast or coastal infrastructure, meaning that waves may run further up beaches and increase flooding.
Waves travelling from a slightly different direction, as they are forecast to do on a fifth of coastline, can change how much sand they shunt along the coast.
– The Times