France Faces a Choice on Eroding Coasts: Tear Down Homes or Build Defenses

Along stretches of the French coast, the sea is advancing faster than planners anticipated a generation ago. Some towns have already demolished buildings; others are lobbying for concrete sea walls instead. The debate has become more formal since France passed the 2021 Climate and Resilience law, which forces at-risk communes to draw official maps of where the coastline is expected to be in 30 and 100 years, according to reporting by The Connexion.

The law that forces towns to choose

The Climate and Resilience law set up a national list of coastal communes required to produce local exposure maps. A first decree dated April 29, 2022 placed the initial communes on the list, including Arzon in the Gulf of Morbihan, according to the town's official website. A second decree published August 1, 2023 added more than 100 further communes, mostly in Charente-Maritime, Finistère and Manche, bringing the total to 242 listed communes, The Connexion reported.

The maps split each commune into two zones under article L. 121-22-3 of the French urban planning code, as summarized by The Connexion. In the zone exposed within 0 to 30 years, new construction is generally refused. In the zone exposed between 30 and 100 years, building can still be authorized, but only if the owner agrees in advance to fund the eventual demolition of the structure once the risk becomes critical.

Demolition has already started

The clearest case so far is the Le Signal apartment building in Soulac-sur-Mer, on the Atlantic coast. Built in 1967 some 200 meters from the shoreline, the four-story block had the sea within 20 meters of its walls by 2014, forcing the evacuation of about 75 flats, France 24 reported. Authorities began demolishing the building on March 3, 2023, after years of asbestos removal work. Former owners only secured compensation after a seven-year legal dispute, with a 2020 ruling ordering the state to reimburse 70% of the homes' original value, according to France 24.

A similar but smaller case played out in Tréffiagat, in Finistère. According to the environmental platform Aquagir, local authorities there demolished two homes on a Friday in June after the shoreline had retreated 30 meters in 30 years. Earlier attempts to hold the line — rock barriers, sand replenishment and wooden pilings costing more than 1 million euros — had failed to stop the retreat. The local authority instead bought out seven houses at market value with plans to demolish all of them, while new sea defenses and nature-based measures are being planned further inland rather than to shield these specific properties, Aquagir reported.

Other towns are fighting to stay

Not every community is accepting retreat. In Ambleteuse, Pas-de-Calais, residents have organized to demand hard infrastructure rather than relocation, according to France 3 Hauts-de-France. A local association is asking for either a substantial rock barrier ("enrochement") or a concrete sea wall ("digue") to protect the dune and nearby homes for decades to come.

About a dozen households there could face expropriation if erosion continues unchecked, and the local yacht club has already lost more than half of its facilities, with some spots losing 3 to 4 meters of coastline in a single year, the same report said. Despite an existing engineering study, no protection project has been launched, and residents say the local authority has not acted.

How many homes are actually at risk

Estimates of the scale differ depending on the time frame and the source. The Connexion, citing French ministry figures, reported in 2023 that roughly 1,000 buildings faced erosion risk by 2028, across more than 500 communes nationally, including 528 holiday residences valued at 167 million euros. Looking further ahead, Aquagir cited an estimate from the French technical agency CEREMA that up to 50,000 homes, worth around 8 billion euros, could be threatened by 2100. For the Gulf of Morbihan specifically, more than 2,000 buildings across its coastal communes are projected to be threatened by shoreline retreat within 100 years, according to local news aggregator Titres Presse.

Environment Minister Christophe Béchu has summarized the pace of loss by saying, as reported by The Connexion, that the equivalent of a football pitch disappears into the sea every week in France. Between 1960 and 2010 the country lost nearly 3,000 hectares of coastline, according to the same report, which cited the Cour des comptes.

Brittany's maps and local pushback

In Arzon, on the Gulf of Morbihan, the commune's exposure maps show the shoreline at two horizons, 2052 (30 years) and 2122 (100 years), covering 356 kilometers of coast across 17 littoral and island communes, according to the town's official site. The municipal council adopted preliminary versions of the maps in June 2026 as part of a wider revision of the local urban plan, and the town has since held walk-in sessions at the town hall to answer residents' questions before the maps are finalized.

• Avoid: stop permitting new construction in zones expected to erode
• Protect: build digues or rock barriers to hold the line
• Adapt: elevate or modify existing buildings
• Nature-based: restore dunes and wetlands as buffers
• Relocate: buy out and move residents away from the coast

Aquagir frames these as the five broad strategies French coastal authorities are weighing commune by commune, noting that protection works that appeared effective in the short term, such as the rock barriers tried in Tréffiagat, were often costly and ultimately did not stop the shoreline from retreating.