|TITLE||MULTI-PROXY EVIDENCES FOR PALEOCEANOGRAPHIC CHANGES IN THE EASTERN MEDITERRANEAN DURING THE HOLOCENE: CONNECTIONS TO REGIONAL AND GLOBAL-SCALE CLIMATIC VARIABILITY PATTERNS|
|AUTHORS||A. Gogou (1), M. V. Triantaphyllou (2), I. Bouloubassi3, K. Kouli (2), G. Rousakis (1), K.-C. Emeis (4), G. Katsouras(1), U. Kotthoff (4), M.Dimiza (2), K.S. Parinos (1), J. Möbius (4), M. Athanasiou (2), V. Lykousis (1)|
- Hellenic Centre for Marine Research, Institute of Oceanography, Anavyssos, Greece
- Faculty of Geology and Geoenvironment, University of Athens, Athens, Greece
- LOCEAN-IPSL, CNRS, Université Pierre et Marie Curie, Paris, France
- University of Hamburg, Institut für Biogeochemie und Meereschemie, D-20146 Hamburg, Germany
|ABSTRACT||Modern and paleo-oceanographic studies highlight the Mediterranean as a climate sensitive region, influenced by both regional and global atmospheric circulation patterns. Within this, the Aegean Sea is characterized by complex atmospheric and hydrologic systems, with effects of atmospheric cooling on water mass formation and inflow of Black Sea water and southern European rivers in its northern borderlands.
Here we present a high-resolution multi-proxy study of five sediment cores collected from the north, central and SE Aegean Sea and the open NE Mediterranean. Fluctuations in alkenone-Uk37 SSTs and multi-proxy indices in our records - including various elemental, isotopic, organic geochemical, micropaleontological and palynological proxies - reveal the occurrence of several distinct warming/ cooling events from the early to mid Holocene. Warm intervals, with most prominent the ‘Holocene Climate Optimum’, linked to increased intensity of the African monsoons and expressed in the marine realm by the deposition of sapropel S1 between ~10.0 to 6.4 ka BP (1). A secondary warm/humid phase was recorded within the mid-Holocene (between 5.4 and 4.3 ka BP), as witnessed by SSTs rise in all records, and the deposition of a sapropel-like layer in our SE Aegean record (2). Repeated cooling events, centered at 8.6, 8.2, 7.8, 7.4 ka, followed by cold spells at 7.0, 6.8, 6.5 ka were probably driven by strengthening of north winds over the Aegean via atmospheric teleconnections (1, 3). According to our proxy-evidences, the highly fluctuating SSTs during those events led to re-ventilation of deep waters and interruptions in the S1 deposition.
A paleoclimatic study for the last 1500 years in the northern Aegean, based on multi-proxy reconstructions from the Medecos-II-M2 high resolution multi-core record revealed various warm and cold intervals, linked to the northern hemisphere and the global scale variability patterns (4). In respect to our findings, the current warming in the reconstructed SSTs might be unprecedented in the context of the past 1500 years.
(1) Marino et al., Quaternary Science Reviews 28, 3246–3262 (2009)
(2) Triantaphyllou et al., Regional Environmental Change 14, 1697-1712 (2014)
(3) Triantaphyllou et al., Geo-Marine Letters 36, 51-66 (2016)
(4) Gogou et al., Quaternary Science Reviews 136, 209-228 (2016)|