Oceanic heat pulses fueling moisture transport towards continental Europe across the mid-Pleistocene transition

• Published in: Quaternary Science Reviews
• Main Authors: Bahr, A., Kaboth, S., Hodell, D., Zeeden, C., Fiebig, J., Friedrich, O.
• Other Authors: Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: Pleistocene; Paleoceanography; North Atlantic; Micropaleontology; Foraminifers; [SDU]Sciences of the Universe [physics]
• Online Access: https://insu.hal.science/insu-03718961; https://doi.org/10.1016/j.quascirev.2017.11.009

International audience The mid-Pleistocene Transition (MPT; approx. 1.2-0.7 Ma), is characterized by growing Northern Hemisphere ice sheets and the shift from a 41 kyr to a 100 kyr glacial-interglacial cyclicity. Concomitant to the growth of large ice sheets, atmospheric and oceanic circulation pattern have changed. One key feature of the North Atlantic is the wind-driven Subtropical Gyre, a major provider of heat and moisture for continental Europe. Here, we investigate changes in the strength and spatial configuration of the Subtropical Gyre during the MPT and its impact on the continental moisture balance. To reconstruct Subtropical Gyre dynamics, we conducted paired δ 18 O and Mg/Ca analyses on the deep-dwelling foraminifera Globorotalia inflata from Iberian Margin Site U1385 yielding thermocline temperature (T therm ) variability between 1400 and 500 ka at the eastern boundary of the Subtropical Gyre. Long-term trends of T therm at Site U1385 oppose the North Atlantic climatic evolution of progressively intensified glacials during the MPT. Particularly, glacials MIS 20 and 18 were marked by warm thermocline waters off Iberia. We infer that a southward shift of the (sub)polar front displaced the source region of thermocline waters within the Subtropical Gyre from high to mid-latitudes. In addition, a strong Mediterranean Outflow Water production during the MPT caused the advection of warm waters to Iberia. Humid conditions during MIS 20 and 18 in SE Europe indicate that atmospheric moisture derived from this warm water might have been advected deep into continental Europe and contributed to enhanced growth of Alpine glaciers.