Researchers say coastal erosion is likely to be more extreme in future because of El Nino and La Nina influences. Andy Short has been keeping an eye on Moruya and Pedro beaches for eight years on the South Coast, and says the latest beach rotations, which are making the northern ends wider and the southern ends narrower, are the biggest he has measured in that period.

Another regular South Coast visitor from Canberra says Meringo beach has lost about two metres of sand in places, evident from two-metre long strands of grass loosely hanging over eroded sections. Exposed rocks have not been seen before in 20 years of visiting the beach.

Professor Short, from Sydney University's School of Geosciences, is co-author of a paper on coastal erosion of beaches that states it could be much worse than previously predicted. A South Coast resident, Professor Short says a persistent southern swell has built up sand on the northern end of smaller beaches.

"If you went to the northern end of Meringo beach you would find it wider than ever. While that is happening, the sands all move from the southern end," he said.

He says the southern swell causing the shifts is characteristic of El Nino conditions: "When we get La Nina, we get more east swell, and east swell pushes it back down the southern end."

Professor Short says this is well documented and happens up and down the coast on two or three kilometre long beaches with headlands. It is not a problem unless property and infrastructure are built at the southern end of the beaches, which has happened on many city beaches.

"Down here it is not a problem, except maybe at Casey's Beach, but none have property at risk at the southern ends."

Twenty years ago, Professor North was among the first researchers to document beach rotation in Australia. He helped in the latest research that suggests an upsurge of El Nino and La Nina events will lead to extreme flooding and erosion in populated regions across the Pacific, including Australia.

The impact of these storms is not presently included in most studies on future coastal vulnerability, which look primarily at sea level rise. New research data, from 48 beaches across three continents and five countries bordering the Pacific Ocean, suggest the predicted increase will exacerbate coastal erosion irrespective of sea level rise affecting the region.

"During enhanced La Ninas we can expect more tropical cyclones and east coast lows off the coast, leading to damaging cyclones and storm surges along the Queensland coast and severe beach erosion along the NSW coast," Professor North says.

"The more benign El Ninos will bring fewer cyclones and long periods of lower southerly waves. These will rotate the beaches to the north, building out the northern ends, while severely eroding the southern corners of the beaches, where most development usually occurs. These impacts will take place irrespective of the amount of sea level rise."

South Coast conservationist John Perkins says the erosion is cyclical. South of Tuross Lake, Potato Point resident Bill Barker agrees. "You see this underwater. I do a bit of scuba diving, sometimes it is all scoured out under the water and other times, sand has come up quite a bit. These events are probably killing creatures attached to rocks, but it is part of the cycle."