Case studies of extreme paleoevents along the French Atlantic coast using sedimentological, dendrochronological and historical approaches

• Main Author: Pouzet, Pierre
• Other Authors: Nantes, Robin, Marc, Maanan, Mohamed
• Format: Thesis
• Language: French
• Published: 2018
• Subjects: geo; envir; North Atlantic; North Atlantic oscillation
• Online Access: http://www.theses.fr/2018NANT2035/document

This study aims to develop several methodological approaches to rebuild past extreme events at the Holocene, millennial and Anthropocene timescales. The methodology is based on a multidisciplinary approach using sedimentology, dendrochronology, climatology and climate history. These approaches were applied to three study sites: the island of Yeu, the Traicts du Croisic and the Petite mer de Gâvres. Several ancient extreme events have been identified and correlated to one another thanks to the multidisciplinary approach. At the Holocene scale, periods of strong stormy impacts seem to be bound to the North Atlantic cooling phases: 600-300, 1700-1100, 2900-2500, 3500-3300, 5500-5100 and 7700-7100 cal y BP. At the millennial scale, however, the connections between the climate change of the Little Ice Age and the North Atlantic Oscillation are more difficult to comprehend. The coupling of sedimentological data with historical archives characterizes sixteen extreme events with high environmental and societal impacts. One of these events, which occurred during the winter of 1351-1352 (n.st) AD, has been qualified as a « Millennium event ». At the Antropocene scale, the sedimentological analysis brings to light four major dates: 1990, 1972, 1940 and 1896 AD. The dendrochronological analysis proved there have been nineteen stormy winters since 1955 AD, which have been confirmed by meteorological archives and reanalysis data. These different approaches enable us to increase with more accuracy our knowledge of coastal hazards. L’objectif de cette recherche est de développer des approches méthodologiques afin de reconstituer les évènements extrêmes du passé aux échelles temporelles holocène, millénaire et anthropocène. La méthodologie repose sur une approche pluridisciplinaire employant la sédimentologie, la dendrochronologie, la climatologie et l’histoire du climat. Ces approches ont été appliquées dans trois terrains d’étude : l’Île d’Yeu, les Traicts du Croisic et la Petite mer de Gâvres. Plusieurs évènements extrêmes ...