Atlantic forcing of Western Mediterranean winter rain minima during the last 12,000 years

• Published in: Quaternary Science Reviews
• Main Authors: Zielhofer, C., Fletcher, W., Mischke, S., De Batist, M., Campbell, J., Joannin, S., Tjallingii, R., El Hamouti, N., Junginger, A., Stele, A., Bussmann, J., Schneider, B., Lauer, T., Spitzer, K., Strupler, M., Brachert, T., Mikdad, A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: Low Lake; North Atlantic
• Online Access: http://hdl.handle.net/11858/00-001M-0000-002C-2E40-2; http://hdl.handle.net/11858/00-001M-0000-002C-2E42-D; http://hdl.handle.net/11858/00-001M-0000-002C-2E43-B

The limited availability of high-resolution continuous archives, insufficient chronological control, and complex hydro-climatic forcing mechanisms lead to many uncertainties in palaeo-hydrological reconstructions for the Western Mediterranean. In this study we present a newly recovered 19.63��m long core from Lake Sidi Ali in the North African Middle Atlas, a transition zone of Atlantic, Western Mediterranean and Saharan air mass trajectories. With a multi-proxy approach based on magnetic susceptibility, carbonate and total organic C content, core-scanning and quantitative XRF, stable isotopes of ostracod shells, charcoal counts, Cedrus pollen abundance, and a first set of diatom data, we reconstruct Western Mediterranean hydro-climatic variability, seasonality and forcing mechanisms during the last 12,000��yr. A robust chronological model based on AMS 14C dated pollen concentrates supports our high-resolution multi-proxy study. Long-term trends reveal low lake levels at the end of the Younger Dryas, during the mid-Holocene interval 6.6 to 5.4��cal ka BP, and during the last 3000 years. In contrast, lake levels are mostly high during the Early and Mid-Holocene. The record also shows sub-millennial- to centennial-scale decreases in Western Mediterranean winter rain at 11.4, 10.3, 9.2, 8.2, 7.2, 6.6, 6.0, 5.4, 5.0, 4.4, 3.5, 2.9, 2.2, 1.9, 1.7, 1.5, 1.0, 0.7, and 0.2��cal ka BP. Early Holocene winter rain minima are in phase with cooling events and millennial-scale meltwater discharges in the sub-polar North Atlantic. Our proxy parameters do not show so far a clear impact of Saharan air masses on Mediterranean hydro-climate in North Africa. However, a significant hydro-climatic shift at the end of the African Humid Period (���5 ka) indicates a change in climate forcing mechanisms. The Late Holocene climate variability in the Middle Atlas features a multi-centennial-scale NAO-type pattern, with Atlantic cooling and Western Mediterranean winter rain maxima generally associated with solar minima.