Scientists and local surfers alike are predicting changes in the surf breaks around Australia’s coastline as climate change wields unexpected impacts on wave heights and ocean swells.

While global warming might improve wave quality in certain regions, Mark Willis, who is Chief Meteorologist at Surfline.com, has published an analysis of wave trends at 16 international surf spots which shows some surfers could have cause for alarm.

The data shows that at 15 of these locations, there’s a 94% decrease in wave height compared to 1979, with surf locations in Australia and Indonesia having the largest downward trend in wave heights.

The surfer’s experience depends on several factors: wave height and intensity, presence of swells, and beach accessibility, says local surfer Joshua Denning-Peattie.

Modelling published by institutions from NOAA to the University of California to the European Union, and recent historic records, already show that climate change will impact wave breaks worldwide – but there’s still little consensus on just how much waves will be affected.

Wave patterns are influenced by several forces which impact the height and intensity of the wave when generated by local winds.

And there are signs that these wind patterns are slowly changing; the EU-funded STILLING project examined a trend for slower average global wind speeds close to the surface of the land in a curious phenomenon known as ‘stilling’- which occurs unevenly around the world. Meanwhile, other research suggests wind forces in the Southern Ocean are becoming stronger.

Wave quality already varies across the planet; there’s a growing body of research showing that the factors behind wave patterns are changing, but not in any consistent or yet well-understood way.

Then there’s storms.

Tropical cyclones are expected to increase in frequency along the north of Australia, which may lead to better swells for local surfers.

But with coastal regions under threat and beaches and break sites also likely to change, there is no certainty around whether the outcome will be good or bad for surfers.

Denning-Peattie believes the New South Wales region is likely to experience smaller swells due to changing low-pressure systems.

This means fewer storms are likely to reach far enough down the coast to stimulate the surf.

Coastal erosion is another big contributor to the changing surf.

“As sea level rises, we’re likely to see the destruction of beaches, especially ones with a break wall,” Denning-Peattie says.

Rising sea level inevitably means the beaches will change. In areas with breakwalls – man-made barriers built to break the waves—beaches might disappear completely.

Denning-Peattie explains that as waves crash into the breakwall they bounce back, removing sand from the beaches as they go.

With no beach, surfers will find it harder to enjoy the water.

However, new spots will be created as the coast warps over the century.

“We could be surfing where my parents’ house is in the next 50 years,” says Denning-Peattie, with a nervous waver to his voice.

While famous breaks may change and well-known spots might lose some of their prestige, the change is unlikely to happen overnight.

What should surfers expect in the meantime?

Science can’t tell you yet.

But Denning-Peattie warns against getting too attached to your favourite sites. They might be gone before you are.

This story is part of Covering Climate Now, a global collaboration of more than 220 news outlets to strengthen coverage of the climate story.