A detailed study of a major storm and its impact on the Australian coast has identified a climate change hazard not previously recognised – as storm patterns change, coastal areas once thought to be safe are likely to be severely affected.

The study of the severe storm event which hit the east coast of Australia in June last year was conducted by a research team led by engineers at the University of NSW. The findings of the study were published in the latest issue of the journal Nature Scientific Reports.

The researchers used a combination of drones, floating sensor buoys, LiDAR sensors, fixed cameras on buildings, quad bikes and jet skis to document the ‘before’ and ‘after’ condition of a 200km stretch of coastline north of Sydney. It was the largest and most detailed pre-storm and post-storm coastline analysis ever carried out.

The study team found that over a period of three days the coastline shifted inland an average of 20m along the entire length of coast as the wave action eroded an estimated 11.5 million cubic metres of sand from the local beaches.

“The amount of erosion was astounding,” Dr Mitchell Harley, who led the study, told the Sydney Morning Herald. “It was akin to the amount of sand shifted by Hurricane Sandy which lashed the east coast of the United States in 2012.”

What the researchers found was that the June 2016 east coast low was only moderately intense, equivalent to a 1-in-5 year event however, it hit from a highly unusual direction – the East. They observed that it is the damaging power of wave energy – and the disruption of long-established storm patterns due to climate change – that present a new danger to coastal areas.

“If you have waterfront property or infrastructure that has previously been sheltered from the impacts of extreme waves, this is worrying news” said Mitchell Harley. “What this study confirms is that simply by changing direction, storms can be many times more devastating, and that’s what we’re facing in many locations as the climate continues to change.”

Professor Ian Turner, director of the Water Research Laboratory at the University of NSW, and a co-author of the study, said sea level rise was no longer the only factor at play when preparing for the impact of climate change on waterfront areas.

“Shifts in storm patterns and wave direction will also have major consequences because they distort and amplify the natural variability of coastal patterns,” he said. “And that’s what’s really worrying: the damage we saw from a moderately intense storm last year is a harbinger of what’s to come.”

“We need to be prepared,” Ian Turner commented. “Not just for the fact that what we consider as ‘king tides’ will be the norm within decades, but that the storms that strike the coast will come from unexpected directions, damaging coastal areas and infrastructure once thought safe from storm damage.”

The full study report is available here