Are unusually big swells an ominous sign for the environment?
If you're a surfer on the East Coast of Australia you’ll know that the entire stretch is about to be hammered by a macking south swell. Most forecasts have the swell peaking at 14 feet with a 15 second period marching up the Tasman Sea in dead south direction. The swell will be accompanied by gale force south winds on Thursday, before more manageable conditions arrive on Friday to set up what could be a classic day of waves.
Surfers with a hankering for size will no doubt be dusting off the Indo guns and priming themselves for their local reefs to be about as big as they can handle. Good news, right? Well, no. A recent study by a group of scientists from Griffith University has found that such rare swells are to become more frequent as the effects of climate change hit home.
Using about 150 model simulations the researchers found about half the world's coastline was "at risk from wave climate change" by the final two decades of this century, assuming we continue at our current levels of greenhouse gas emissions.
The study found that many ocean regions can expect annual mean significant wave height to increase between 5 and 15 per cent compared with a 1979-2004 baseline. For Australia, the South Australia and Victoria coasts especially are really going to be impacted by the Southern Ocean changes.
Not only are waves getting bigger, but they are also becoming more powerful. The mean period between waves was projected to increase by a similar range of 5 to 15 percent. Bigger swells with longer period is basically what every surfer hopes for. Unfortunately, this wave climate change comes with considerable costs to the population as a whole. The more forces pounding the coast will have a serious impact on coastal infrastructure.
The study also found that the direction of the waves will also tilt, although it didn’t say in which direction. For my homebreak, I’d be happy with a tilt to the north-east, however again, these changes could have devastating effects. Even small changes in the direction of waves can cause large-scale chaos to the coastline as sand gets scoured from some beaches and dumped on others.
“Storms are changing, the wind fields are changing around the world, and that's going to have inevitable consequences on how our waves are striking the coast and consequently how our coastline is going to respond," Joao Morim, a PhD candidate at Griffith University and lead author of the paper, said. “Satellites had identified an increase of about 3 percent in wave energy over the past half-century.”
Of course, the power is still in our hands if we want to save the coastline from mass destruction. Morim has stated that if emissions can be limited sufficiently to contain global warming to within the Paris climate target of 2 degrees compared with pre-industrial levels, the projected wave changes do not stand out from the natural variability.”
Now it is this change in natural variability that will see some huge waves being ridden up and down the coast over the next few days. However it’s also another warning that our climate, coastline, and oceans are changing within our lifetime and as surfers we are, literally, at the frontline.