Two of Ulster's best loved beaches are disappearing after sea walls were built, a coastal geologist has warned.
And the chairman of the new Northern Ireland Coastal and Marine Forum has predicted that other north coast beaches could go the same way as Portballintrae beach and the West Strand in Portrush.
Coastal geologist Professor Andrew Cooper, of the University of Ulster, warned that the two beaches have become narrower and narrower since their sea walls were built.
And he said the natural beach/dune system serves to protect coasts from sea storms - while erecting man-made sea defences can do the opposite.
"You might think a wall is enhancing the protective capabilities of the coast - but in fact it's reducing them," he said.
"The effect is that the beach in front of those walls ends up disappearing.
"Beaches such as Benone or Whitepark Bay are good natural defences against sea storms."
Natural beaches and dunes act as buffers against wave energy, temporarily eroding as a sea storm hits and later returning to their pre-storm state, Prof Cooper said.
"When a wall is built behind a beach, it stops the coast eroding and the energy that would have been used bounces off the wall and carries the sand out to sea," he said.
"There is no dune to take the extra sand from and break the energy of the storm."
Prof Cooper said it was probably too late for West Strand and Portballintrae, which have narrowed since their sea walls were built in the 1960s and 1980s respectively, but lessons can be learned by developers in other scenic coastal areas.
"With a wall you can protect the land behind the beach, but you lose the beach. People think walls protect the land, but they don't always appreciate that they have a negative effect on the beach," he said.
"We need to make sure we don't do it elsewhere. There is a temptation to build closer and closer to the coast.
"As long as we don't build houses or roads there and we leave space for the beaches to move backwards and forwards, we'll be all right.
"There is always a demand for building things close to the sea. West Strand and Portballintrae are good examples of how not to live close to the sea."
The new forum has been set up to pioneer an integrated approach to managing the coast, and Prof Cooper believes coastal issues are likely to rise up the political agenda with the increasing effects of climate change.
"The coast is our first line of defence against climate change and global warming," he said.
"If we get rises in sea level and increased storminess, it's important that we deal with them in a sensitive way - otherwise we'll end up with a wall right round Northern Ireland and no beaches."