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

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doi: 10.1016/j.quascirev.2017.02.013
Author(s): Oliveira, Dulce; Sánchez Goñi, Maria Fernanda; Naughton, Filipa; Polanco-Martinez, J. M.; Jimenez-Espejo, Francisco J.; Grimalt, Joan O.; Martrat, Belen; Voelker, Antje H. L.; Trigo, Ricardo; Hodell, David; Abrantes, Fatima; Desprat, Stéphanie
Author Affiliation(s): Primary:
PSL Research University, École Pratique des Hautes E2.tudes, Pessac, France
Instituto Portugues do Mar e da Atmosfera, Portugal
Japan Agency for Marine-Earth Science and Technology, Japan
CSIS/Institute of Environmental Assessment and Water Research, Spain
Universidade de Lisboa, Portugal
University of Cambridge, United Kingdom
Volume Title: Quaternary Science Reviews
Source: Quaternary Science Reviews, Vol.161, p.1-17. Publisher: Elsevier, International. ISSN: 0277-3791
Note: In English. 144 refs.; illus., incl. 1 table, sketch map
Summary: Marine Isotope Stage 31 (MIS 31) is an important analog 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.
Year of Publication: 2017
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Atlantic Ocean; Biomarkers; Biostratigraphy; Cenozoic; Chronostratigraphy; Climate change; Climate forcing; Cores; Expedition 339; IODP Site U1385; Integrated Ocean Drilling Program; Interglacial environment; Isotope ratios; Isotopes; Lower Pleistocene; MIS 31; Marine sediments; Mediterranean region; Microfossils; Miospores; North Atlantic; Northeast Atlantic; O-18/O-16; Orbital forcing; Oxygen; Paleoclimatology; Palynomorphs; Pleistocene; Pollen; Pollen diagrams; Quaternary; Reconstruction; Sediments; Stable isotopes; Statistical analysis; Time series analysis; Vegetation; Western Mediterranean region
Coordinates: N373417 N373417 W0100719 W0100720
Record ID: 2018044674
Copyright Information: GeoRef, Copyright 2018 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands