Official Report: Bordeaux, Nantes and La Rochelle Face Sea Level Rise Threat by 2050

In France, sea level rise is no longer seen as a distant possibility; on the contrary, it has become a concrete reality approaching day by day for coastal cities. An official report published in Eylül 2025 by the Bureau of Geological and Mining Research (BRGM) revealed the retreat that will occur on the country's coastlines with clear figures. The report in question was prepared at the request of the Ministry of Ecological Transition and adapted the global projections of the Intergovernmental Panel on Climate Change (IPCC) to France's local dynamics. Accordingly, sea levels on the French coast are expected to rise by approximately 25 centimeters by 2050. This situation directly threatens numerous settlements, including major cities such as Bordeaux, Nantes and La Rochelle.

In their assessment, researchers based their findings on TRACC, the official adaptation scenario in which global warming will reach 3 degrees by 2100 and 4 degrees in France. Within the framework of this scenario, it is calculated that sea levels will rise by 25 centimeters in 2050 and 65 centimeters by 2100. The projections in question involve a comprehensive examination of fourteen major ports in metropolitan France and overseas territories. However, it should not be forgotten that additional dynamics such as wave movements, tidal phenomena, and severe storms will be added on top of these averages. Therefore, during periods of severe weather events, it will be inevitable for sea levels to reach levels far exceeding these predictions.

One of the most striking points emphasized in the report is the bitter danger facing cities established on estuaries and river mouths. The inland advance of seawater along rivers leaves the low-lying neighborhoods of these cities directly facing the risk of flooding. For instance, Bordeaux must anticipate that its docks along the Garonne River will be subjected to much more frequent floods. Similarly, the city of Nantes, built on the Loire River, exhibits a great vulnerability to the rising sea. This situation proves that the increase in water levels deeply affects not only the open sea but also inland waterways.

The example of La Rochelle clearly illustrates the devastating potential of climate change through the 2010 Xynthia Storm, which has not been erased from memories. On that tragic night in 2010, the resulting floods caused dozens of people to lose their lives on the Atlantic Ocean coast. Scientists and authorities warn that the continued rise of sea levels at the current momentum will make the effects of similar disasters much more destructive. In this context, concerns are growing that the dikes and dams already built may no longer be sufficient to protect this population. The pushing of current infrastructure to its limits is forcing local governments to develop new and radical defense strategies.

Coastal local governments can no longer ignore this massive problem and must choose a path between protection, adaptation, or retreat against the sea. Some municipalities have even entered the planning stage to move economic activities and settlements inland to safer areas to reduce risks. On the other hand, some localities are continuing their efforts to reinforce and elevate existing dikes in order to gain more time. The report also reminds us of the fact that sea levels will continue to rise for centuries after 2100. However, limiting global greenhouse gas emissions through decisions to be made in the coming decades will directly determine the extent of the trauma that future generations will experience, and the importance of every sector in shaping this transition process is crucial.