Caen, the city that has already cancelled real estate projects for fear of rising waters

Conceived at the beginning of the 2010s, the "Nouveau Bassin" real estate program was to create 2.300 homes and 35.000 m2 of commercial space on a Charbonnages de France industrial wasteland.

"It will not happen," says the general manager of the local public development company (SPLA) "Caen Presqu'île" in charge of the project, Thibaud Tiercelet.

Instead, a promenade is being built while waiting for a study of hydraulic dynamics over the entire Orne estuary, focusing on the rise in sea level downstream and the flow of the Orne upstream.

In 2023, when all the authorizations were finally obtained to start the work, Mr. Tiercelet was alerted by an assembly of experts responsible for determining the impact of climate change on the region (called the "Norman IPCC", with no connection to the group of climate experts mandated by the UN).

The urban planner asked to meet Joël Bruneau, then mayor of Caen and president of the urban community of Caen-la-mer, to present the data to him.

"For us, the reference is the IPCC: in 2017 the estimate of the rise in sea level was 20 cm by 2100, in 2020 it was 60 cm, in 2023 we had gone to 1 meter," recalls Thibaud Tiercelet.

The IPCC predicts a probable rise of between 40 and 80 cm in sea level by 2100, while warning that poorly understood factors were not taken into account, such as the melting of ice caps, which could significantly boost the phenomenon. In any case, the IPCC recommends that cities anticipate beyond the most probable intervals.

The end of a model

Currently, the quay is only 70 cm above the water of the canal. "If the sea rises by one meter, here it floods every week," the director decides.

As for the level of the canal, it is now regulated by a lock, "which has only 50 cm of clearance at high tide", notes Mr. Tiercelet. In a few decades it will no longer fulfill its role.

The priority is to "protect urban areas without creating new difficulties," he explains.

Emmanuel Renard, vice-president for planning and land for the urban community of Caen-la-mer, estimates the time frame for this type of investment at "around a hundred years" and is therefore relying on "high, most probable hypotheses".

According to the elected official, the water will rise "by at least one meter, whether it will be in 2070, in 2100, in 2120, no one can say." Climate scientists emphasize that the uncertainty concerns the magnitude and pace of the rise in water levels, but that this rise will take place.

The president of the urban community, Joël Bruneau, therefore decided to stop the project, as well as the extension of the tram and an access footbridge, recalls Mr. Renard, estimating that "stopping everything two years later would have been expensive."

To replace the "New Basin" project, the director of the public development company imagines "transitional urban planning over 40 years with temporary occupations" such as student housing or craft workshops on these lands where disused warehouses await their destruction.

With the increasingly frequent rise of sea water, through the estuary or the water tables, this freshwater ecosystem will gradually become salinized.

The tree species that will soon be planted around the promenade, currently being decontaminated, have been chosen to adapt to this new ecosystem.

"It is the end of a 170-year-old model, of the technological explosion which enabled the era of major works, of control of our environment, we will now have to adapt," concludes Thibaud Tiercelet.