Géohistoire des tempêtes et submersions marines depuis 1 000 ans : quelles interprétations climatiques dans l’ouest de la France ?

• Published in: Bulletin de l'Association de géographes français
• Main Authors: Pouzet, Pierre, Athimon, Emmanuelle, Maanan, Mohamed
• Format: Article in Journal/Newspaper
• Language: French
• Published: Association AGF 2022
• Subjects: climatologie; sédimentologie; sources historiques; côte atlantique; Climatology; Sedimentology; Historical sources; Atlantic coast; lang; hist; Tempêtes; North Atlantic; North Atlantic oscillation
• Online Access: http://journals.openedition.org/bagf/8168

In the current climate change context, studying coastal risks involves considering the hazard’s historical fluctuations to understand the ocean-climatic parameters that guide its variability. Thanks to the coupling of sedimentological and historical data, fifteen intense storms were extracted from a core sampled in the Traicts of the Croisic, while 128 impacting events were recorded by historical sources during the last millennium. The synthesis of sedimentological and historical works carried out in western France highlights three common stormy periods estimated at approximately 1330 – 1360 AD, 1570 – 1620 AD and 1690 – 1720 AD. These three periods are part of climate pejoration phases, or of cold tendencies. While storm activity appears to increase during North Atlantic Oscillation (NAO)’s positive phases, no strict correlations are established. The change in position of the “mid-latitude storm tracks” could also explain some trajectories. To put these results into perspective and offer new prospects to improve French coastal risk management, the limits of this study are also discussed. This approach must be more exhaustive to specify the tempestuous chronology, but also extend it to the entire French Atlantic coast and thus consider all the mechanisms likely to guide their formation in Western Europe. Dans le contexte actuel lié au changement climatique, l’étude des risques côtiers implique la considération des fluctuations historiques de l’aléa pour comprendre les paramètres océano-climatiques guidant sa variabilité. Grâce au couplage entre données sédimentologiques et historiques, quinze tempêtes intenses ont été extraites d’un carottage prélevé aux Traicts du Croisic, tandis que 128 évènements impactant ont été recensés par les sources historiques durant le dernier millénaire. La synthèse des travaux sédimentologiques et historiques réalisée dans l’ouest de la France met en lumière trois périodes tempétueuses communes estimées à environ 1330 – 1360 ap. J.-C., 1570 – 1620 ap. J.-C. et 1690 – 1720 ap. ...