Combination of insolation and ice-sheet forcing drive enhanced humidity in northern subtropical regions during MIS 13

• Published in: Quaternary Science Reviews
• Main Authors: Oliveira, Dulce, Desprat, Stéphanie, Yin, Qiuzhen, Rodrigues, Teresa, Naughton, Filipa, Trigo, Ricardo M., Su, Qianqian, Grimalt, Joan O., Alonso-Garcia, Montserrat, Voelker, Antje H. L., Abrantes, Fátima, Sánchez Goñi, Maria Fernanda
• Other Authors: École Pratique des Hautes Études (EPHE), Université Paris Sciences et Lettres (PSL), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: Mid-Brunhes event; Interglacial MIS 13; Mediterranean vegetation; Model-data comparison; Insolation; Ice-sheets; [SDU]Sciences of the Universe [physics]; Ice Sheet
• Online Access: https://insu.hal.science/insu-03678686; https://doi.org/10.1016/j.quascirev.2020.106573

International audience Marine Isotope Stage (MIS) 13, ∼533-478 ka, has received particular attention due to the unexpected enhancement of monsoon systems under a cool climate characterized by lower atmospheric CO 2 and larger ice volume than many other interglacials. Key questions remain about its regional expression (intensity, climate variability, length), and underlying forcing factors, in particular at the mid-latitudes. Here we examine the SW Iberian vegetation, terrestrial climate and sea surface temperature (SST) variability during MIS 13 by combining pollen and biomarker data from IODP Site U1385 with climate-model experiments. We show, for the first time, that despite strong precessional forcing, MIS 13 stands out for its large forest expansions with a reduced Mediterranean character alternating with muted forest contractions, indicating that this stage is marked by a cool-temperate climate regime with high levels of humidity. Results of our data-model comparison reveal that MIS 13 orbitally driven SW Iberian climate and vegetation changes are modulated by the relatively strong ice-sheet forcing. We find that the Northern Hemisphere ice-sheets prescribed at the MIS 13 climate optimum reinforce the insolation effect by increasing the tree fraction and both winter and summer precipitation. We propose that the interactions between ice-sheets and major atmospheric circulation systems may have resulted in the persistent influence of the mid-latitude cells over the SW Iberian region, which led to intensified moisture availability and reduced seasonality, and, in turn, to a pronounced expansion of the temperate forest.