Increase of storm events during the Holocene cold events in NW Mediterranean Sea

This paper present a high resolution record of paleostorm events in the French Mediterrannean coast over the past 7000 years based on a long sediment core from lagoonal environment in Gulf of Lions. Using a multi-proxies approach on core associating grain size, faunal analysis, with a chronology derived from radiocarbon dates, we reconstruct Mid to Late Holocene history of backbarrier deposits in relation to landfalling activity. Even if change in lagoon geomorphological setting over the Holocene does not allow to compare storm events in terms of intensity trough time, we have recorded seven periods of increase in storm activity at 6200, 5400, 4600-4200, 3600-3100, 2600, 1900-1500 yr cal B.P. and over the Little Ice Age (450 and 50 yr cal B.P.). Whereas the Medieval Warm Period (1200-700 yr cal B.P.) is characterized by a low storm activity. These evidences of changes in coastal hydrodynamic are in phase with those observed over the North Atlantic and correspond to Holocene cooling evidenced associated to decreases of SST in the North Atlantic. These periods of low SST observed in North Atlantic can produce a stronger meridional temperature gradient and a southward position of the westerlies during these periods. We hypothesize here that this increase in storm activity during Holocene cold events over the North Atlantic and Mediterranean region was probably due to thermal gradient increase leading to enhanced lower tropospheric baroclinicity over a large Central Atlantic-European domain. These results demonstrate that North Atlantic region influence the Mediterranean climate at Holocene timescale, in relation to severe storm activity