SOULAC-SUR-MER, France (Reuters) - When it was built at the end of the 1960s on one of France's most glorious Atlantic coastlines, the beach was over 200 metres away.

Today, the hulk of the 80-flat Le Signal apartment block perches precariously on a dune just metres from the water and local authorities are tearing it down before it tumbles.

Four stories high, it targeted vacationers in Soulac-sur-Mer, at the northernmost tip of the Gironde estuary in southwest France, known for its broad golden beaches and pine forests.

But with beaches disappearing at a rate of about 2.5 metres per year in past decades, Soulac-sur-Mer suffered some of the fastest coastal erosion in France. By 2010, the ocean was lapping at the dune on which Le Signal was built.

A view shows a sea wall on the beach that protects sand dunes from erosion along the Atlantic coast in Soulac-sur-Mer, France, Feb. 9, 2023. (Stephane Mahe/REUTERS)

In 2014, the local government decided to relocate the building's inhabitants and began the long process of expropriation and removing asbestos before starting demolition earlier this month.

Behind a fence on a sunny day in February, residents and vacationers watched as an excavator bit pieces out of Le Signal's empty hulk.

"The demolition of this building puts a finger on a key question of our times, climate change and its impact on ocean levels," said 71-year-old local resident Guy Bouyssou, who also feared the village itself, just north of Le Signal, could be the next in line for water damage.

People look at the demolition of the Signal building, a seaside block of flats that had to be evacuated in 2014 due to erosion on the Atlantic Ocean coast, in Soulac-sur-Mer, France, Feb. 9, 2023. (Stephane Mahe/REUTERS)

Adrien Privat, an official at French coast protection agency Conservatoir du Littoral, said that threat is very real.

"Le Signal's situation is largely symbolic for what is happening in terms of coastal erosion France," he said.

Privat said global warming was having a major impact as higher average sea levels exacerbate other factors that cause erosion and make shorelines more vulnerable to storms.

A man walks past the Signal building, a seaside block of flats which had to be evacuated in 2014 due to erosion on the Atlantic Ocean coast, during its demolition in Soulac-sur-Mer, France, Feb. 8, 2023. (Stephane Mahe/REUTERS)

He added the boxy building was a typical example of the extensive build-up of coastal areas in the second half of the 20th century, when urban planners had little regard for the fact that shorelines are dynamic and ever-changing.

"We estimate that some 50,000 residences are in zones that will require them to be moved by the end of the century. All of France's coasts are under threat, and sandy coastlines more than rocky ones," he said.

A view shows the Signal building, a seaside block of flats that had to be evacuated in 2014 due to erosion on the Atlantic Ocean coast, during its demolition in Soulac-sur-Mer, France, Feb. 8, 2023. (Stephane Mahe/REUTERS)

He said ever-rising sea levels and increasingly violent storms made it impossible to let people live in Le Signal without costly shore protection measures that could also have negatively impacted nearby shorelines.

He added that long expropriation procedures and the struggle to finance an environmentally sound demolition was a necessary rehearsal for things to come.

"Le Signal is a warning for what could happen in other zones and for the need to prepare for it now," he said.

Reporting by Stephane Mahe; writing by Geert De Clercq; editing by Josie Kao.

Thumbnail image: People look at the demolition of the Signal building, a seaside block of flats that had to be evacuated in 2014 due to erosion on the Atlantic Ocean coast in Soulac-sur-Mer, France, on Feb. 9, 2023. (Stephane Mahe/REUTERS)