Unexpected weak seasonal climate in the western Mediterranean region during MIS 31, a high-insolation forced interglacial

Oliveira, Dulce and Sánchez Goñi, Maria Fernanda and Naughton, Filipa and Polanco-Martínez, J.M. and Jimenez-Espejo, Francisco J. and Grimalt, Joan O. and Martrat, Belen and Voelker, Antje H.L. and Trigo, Ricardo and Hodell, David and Abrantes, Fátima and Desprat, Stéphanie (2017) Unexpected weak seasonal climate in the western Mediterranean region during MIS 31, a high-insolation forced interglacial. Quaternary Science Reviews, 161. pp. 1-17. ISSN 0277-3791 DOI 10.1016/j.quascirev.2017.02.013

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Official URL: http://doi.org/10.1016/j.quascirev.2017.02.013

Abstract

Marine Isotope Stage 31 (MIS 31) is an important analogue for ongoing and projected global warming, yet key questions remain about the regional signature of its extreme orbital forcing and intra-interglacial variability. Based on a new direct land-sea comparison in SW Iberian margin IODP Site U1385 we examine the climatic variability between 1100 and 1050 ka including the “super interglacial” MIS 31, a period dominated by the 41-ky obliquity periodicity. Pollen and biomarker analyses at centennial-scale-resolution provide new insights into the regional vegetation, precipitation regime and atmospheric and oceanic temperature variability on orbital and suborbital timescales. Our study reveals that atmospheric and SST warmth during MIS 31 was not exceptional in this region highly sensitive to precession. Unexpectedly, this warm stage stands out as a prolonged interval of a temperate and humid climate regime with reduced seasonality, despite the high insolation (precession minima values) forcing. We find that the dominant forcing on the long-term temperate forest development was obliquity, which may have induced a decrease in summer dryness and associated reduction in seasonal precipitation contrast. Moreover, this study provides the first evidence for persistent atmospheric millennial-scale variability during this interval with multiple forest decline events reflecting repeated cooling and drying episodes in SW Iberia. Our direct land-sea comparison shows that the expression of the suborbital cooling events on SW Iberian ecosystems is modulated by the predominance of high or low-latitude forcing depending on the glacial/interglacial baseline climate states. Severe dryness and air-sea cooling is detected under the larger ice volume during glacial MIS 32 and MIS 30. The extreme episodes, which in their climatic imprint are similar to the Heinrich events, are likely related to northern latitude ice-sheet instability and a disruption of the Atlantic Meridional Overturning Circulation (AMOC). In contrast, forest declines during MIS 31 are associated to neither SST cooling nor high-latitude freshwater forcing. Time-series analysis reveals a dominant cyclicity of about 6 ky in the temperate forest record, which points to a potential link with the fourth harmonic of precession and thus low-latitude insolation forcing.

Item Type: Article
Uncontrolled Keywords: 2017AREP, IA72,
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Journal or Publication Title: Quaternary Science Reviews
Volume: 161
Page Range: pp. 1-17
Identification Number: 10.1016/j.quascirev.2017.02.013
Depositing User: Sarah Humbert
Date Deposited: 24 Apr 2017 20:51
Last Modified: 28 Apr 2017 16:37
URI: http://eprints.esc.cam.ac.uk/id/eprint/3949

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