Coastal response to climate change: Mediterranean shorelines during the Last Interglacial (MIS 5)

The response of shorelines to climate change is controlled by fall and rise of the sea level and by the alteration of the coastal environment due to changing fluvial discharge and biological activity. In the Mediterranean this response is complicated by the geographic proximity of the North Atlantic and the African Monsoon climate systems, by a time and space specific interaction of eustatic and water-load components of sea level and by the mid-latitudinal time lag between orbital forcing and terrestrial response. Here, six Mediterranean coastal records are presented which contribute to our understanding of how mid-latitudinal coasts respond to orbital forcing. The sediment sequences show sharp switches between siliciclastic- and carbonate-dominated nearshore environments where carbonate-rich sediments are composed of oolitic grainstones. From modern analogues it is deduced that the oolitic sediments represent a period of relatively high annual sea-surface temperature and lack of fluvial discharge. The warm-arid period was recorded at ∼114 ka on the southeast Iberian coast, at ∼113 ka on the Levant coast, at ∼110 ka on the coast west of the Nile delta and at ∼83 ka on the north Saharan coast. It lasted 10–20 ka in east (Levant coast) and west (Iberian coast) and lasted 40 ka or more in the central-south of the east Mediterranean. Timing and duration of the coastal proxy allow inferring instantaneous and dominant response to external forcing in the east and west and delayed and prolonged response due to dominant regional forcing in the centre of the East Mediterranean. A 9 m eustatic sea-level highstand during MIS 5e is suggested with a start of the subsequent sea-level fall at ∼118 ka while evidence for multiple MIS 5e highstand and a highstand during MIS 5a remain elusive.

► Mediterranean coastal response to orbital forcing during the Last Interglacial.
► Response is dominated by NAO, little evidence for African monsoon impact.
► Space-specific dominance of external forcing of coastal response.
► Mediterranean sea level change is time and space specific with few coasts picturing the eustatic component only.
► MIS 5e eustatic highstand at ∼9 m above sea level.