Enhanced Mediterranean water cycle explains increased humidity during MIS 3 in North Africa

Rogerson, Michael, Dublyansky, Yuri, Hoffmann, Dirk L., Luetscher, Marc, Töchterle, Paul and Spötl, Christoph (2019) Enhanced Mediterranean water cycle explains increased humidity during MIS 3 in North Africa. Climate of the Past, 15 (5). pp. 1757-1769. ISSN 1814-9332

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Official URL: https://doi.org/10.5194/cp-15-1757-2019

Abstract

We report a new fluid inclusion dataset from northeastern Libyan speleothem SC-06-01, which is the largest speleothem fluid inclusion dataset for North Africa to date. The stalagmite was sampled in Susah Cave, a low-altitude coastal site, in Cyrenaica, on the northern slope of the Jebel Al-Akhdar. Speleothem fluid inclusions from the latest Marine Isotope Stage (MIS) 4 and throughout MIS 3 (∼67 to ∼30 kyr BP) confirm the hypothesis that past humid periods in this region reflect westerly rainfall advected through the Atlantic storm track. However, most of this moisture was sourced from the western Mediterranean, with little direct admixture of water evaporated from the Atlantic. Moreover, we identify a second moisture source likely associated with enhanced convective rainfall within the eastern Mediterranean. The relative importance of the western and eastern moisture sources seems to differ between the humid phases recorded in SC-06-01. During humid phases forced by precession, fluid inclusions record compositions consistent with both sources, but the 52.5–50.5 kyr interval forced by obliquity reveals only a western source. This is a key result, showing that although the amount of atmospheric moisture advections changes, the structure of the atmospheric circulation over the Mediterranean does not fundamentally change during orbital cycles. Consequently, an arid belt must have been retained between the Intertropical Convergence Zone and the midlatitude winter storm corridor during MIS 3 pluvials.

Item Type: Article
Subjects: F600 Geology
F800 Physical and Terrestrial Geographical and Environmental Sciences
Department: Faculties > Engineering and Environment > Geography and Environmental Sciences
Depositing User: John Coen
Date Deposited: 09 Jun 2020 09:57
Last Modified: 09 Jun 2020 10:00
URI: http://nrl.northumbria.ac.uk/id/eprint/43384

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