Perspectives d’évolution de la population des départements littoraux à l’horizon 2050

• According to INSEE studies, the population of coastal departments should grow by 14.1% between 2013 and 2050, an increase of 3.6 million inhabitants, while non-coastal departments should grow by 11.5%, adding 4.7 million inhabitants. Metropolitan coastal departments could gain 3.3 million inhabitants (+14.1%), especially along the Atlantic arc and in Occitanie, while overseas departments could gain more than 300,000 (+15.1%), particularly in Mayotte and French Guiana. Under this scenario, coastal departments could account for 39% of the French population in 2050. • The population growth in coastal departments observed to date should not slow down. • As the previous prospective study for 2007-2040 already showed (see factsheet), assuming recent demographic trends continue (central scenario), the population of coastal departments should grow faster than non-coastal departments between 2013 and 2050, with respective increases of 14.1% and 11.5%. • The population of coastal departments should increase by 3.6 million inhabitants, nearly 3.3 million in metropolitan France, representing a 14% rise, and more than 300,000 overseas, a 15% increase. • Under this scenario, coastal departments would account for 39% of the French population in 2050, and their contribution to overall French population growth would be 44% over the period studied.

• Between 2009 and 2014, metropolitan coastal municipalities accounted for 11% of demographic growth in coastal departments, while overseas municipalities represented 65% of demographic growth in overseas departments. Maintaining these proportions, the population of coastal municipalities could increase by 570,000 inhabitants and reach nearly 8.7 million by 2050. • Between 2009 and 2014, metropolitan coastal municipalities accounted for 11.2% of demographic growth in coastal departments, with a ratio of 65.0% overseas. If these ratios persist during 2013-2050, the population of coastal municipalities could increase by 570,000 inhabitants under the central scenario and reach nearly 8.7 million in 2050.

According to INSEE's central scenario, over one-third (35%) of inhabitants in metropolitan coastal departments would be over 60 by 2050. This share would double overseas, rising from 15% in 2013 to 27% in 2050. Many metropolitan coastlines (Corsica, Central-Atlantic, Roussillon, Southern New Aquitaine, English Channel, Morbihan, Var) and Caribbean departments would have aging indices above 2 in 2050, meaning twice as many residents over 60 as under 20.

Managing population growth will be an important territorial planning issue at the coast and inland to balance different uses of this space: primary activities, urban expansion, protected areas, service economy, and others.

• Using INSEE's central scenario, population growth would not be uniform across metropolitan coastlines between 2013 and 2050. The population of English Channel–North Sea coastal departments would increase only 4.1%, while the Atlantic arc would see strong growth: +23.5% in North Atlantic-Western Channel and +24.8% in South Atlantic. Growth would be moderate around the Mediterranean: +13.0%. • The ten coastal departments of the Atlantic arc alone would account for one-quarter (24.6%) of France's demographic growth over this period, adding 2 million inhabitants.

• Overseas, the situation of different departments is even more dispersed. • Under the central scenario, Mayotte's population would more than double from 2013 to 2050, rising from 215,000 to 490,000 inhabitants. French Guiana's population would also grow substantially, increasing nearly 60% with 141,000 new inhabitants. Réunion's growth would be more modest at +9%, below the national average. Finally, under the central scenario, the Caribbean population could decline significantly. This decline would be sharper in Martinique than Guadeloupe, with the Caribbean losing 175,000 inhabitants over the period. This decline would result from very rapid population aging and deaths exceeding births, along with negative migration balances.

According to INSEE's central scenario, the population of coastal departments should age significantly in both metropolitan France and overseas from 2013 to 2050.

The aging index (population over 60 divided by population under 20) would increase 56% in metropolitan coastal departments and 107% overseas, compared to a national average of 53%. Those over 65 could represent more than one-third of the metropolitan coastal population in 2050 (35%) versus 25% in 2013. This would affect 27% of the overseas population, nearly double the current share of 15%.

In many coastal departments, seniors could be twice as numerous as residents under 20 in 2050, including Corsica and the Caribbean, Central-Atlantic (Vendée and Charente-Maritime), the Channel, Morbihan, Aude, Var, Landes, Pyrénées-Atlantiques, and Pyrénées-Orientales.

The aging index would be significantly lower in the Mayotte Archipelago, French Guiana, and Réunion, the only coastal departments where those under 20 could still represent more than one-quarter of the population in 2050.

According to INSEE's central scenario, the natural balance over 2013-2050 would be positive in half the coastal departments, including all overseas departments except Martinique, as well as most departments of the Eastern Channel–North Sea coast from Nord to Calvados, plus Bouches-du-Rhône, Hérault, Loire-Atlantique, Ille-et-Vilaine, and Gironde, with major dynamic urban centers (Montpellier, Nantes, Rennes, Bordeaux).

Conversely, natural balances would be negative in aging coastal departments such as Provence, Central-Atlantic, Brittany, Corsica, and Roussillon.

• Under the central scenario, coastal departments would remain equally attractive during 2013-2050 with very strong migration balances, except for overseas departments and Eastern Channel–North Sea coast departments (Nord, Pas-de-Calais, Seine-Maritime) and Bouches-du-Rhône. • Migration balance would be very strong in Corsica, Central-Atlantic (Vendée and Charente-Maritime), Morbihan, Southern New Aquitaine (Landes and Pyrénées-Atlantiques), and Roussillon (Pyrénées-Orientales and Aude), all located south of Morbihan on the Atlantic or Mediterranean.

• Methodology • INSEE published population projections for all French departments through 2050, based on projections for all of France released by INSEE in November 2016. • INSEE developed the Omphale model for this purpose, enabling subnational projections by projecting age pyramids year by year for different territories using three parameters: fertility, mortality, and migration. • Different scenarios are developed based on assumptions. This factsheet uses only the central scenario, applying recent national trends at the departmental level: +70,000 annual net migration with foreign countries, stable fertility, and life expectancy gains. Nationally, female and male life expectancy would reach 90.3 and 86.8 years respectively in 2050, compared to 85.0 and 78.7 years in 2013. • Two parameters are covered in this factsheet: • Population number evolution; • Evolution of the aging index (share of population over 60 divided by share of population under 20).