Climate Change: Rising Seas, Shifting Shores

Climate change impacts manifest starkly on French coasts. Sea level rise, averaging 3.3 mm annually but accelerating, combines with stronger storms to increase erosion and flooding. The Aquitaine coast loses 1-3 meters annually, with some sections retreating 10 meters in single storms. Historic ports like Saint-Malo and La Rochelle face increasing flood frequency, forcing expensive adaptation measures.

Species distributions shift northward as waters warm. Mediterranean species like triggerfish and barracuda now appear regularly off Brittany. Traditional fishing grounds empty as target species move to cooler waters. Oyster farmers battle new diseases that thrive in warmer conditions. Wine producers in coastal regions adjust varietals and techniques as temperature and precipitation patterns change.

Ocean acidification, the "other CO2 problem," threatens shell-forming organisms. As oceans absorb atmospheric carbon dioxide, pH drops make it harder for oysters, mussels, and other calcifiers to build shells. Early life stages prove most vulnerable—oyster larvae mortality increases dramatically at pH levels projected for 2100. This threatens not just aquaculture but entire food webs based on shelled organisms.

Extreme events increase in frequency and intensity. The 2003 heatwave killed extensive posidonia meadows in shallow Mediterranean waters. Winter storms in 2013-2014 reshaped entire Atlantic beaches, destroying infrastructure and forcing reassessment of coastal defense strategies. These events, once considered centennial, now occur every decade or less, outpacing natural recovery and human adaptation capacity.