Subsurface heat channel drove sea surface warming in the high-latitude north atlantic during the Mid-Pleistocene transition

• Published in: Geophysical Research Letters
• Main Authors: Catunda, Maria Carolina Amorim, Bahr, Andre, Kaboth-Bahr, Stefanie (Dr.), Zhang, Xu, Foukal, Nicholas P., Friedrich, Oliver
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: ddc:550; Institut für Geowissenschaften; Ice Sheet; North Atlantic; Planktonic foraminifera
• Online Access: https://publishup.uni-potsdam.de/frontdoor/index/index/docId/67460; https://doi.org/10.1029/2020GL091899

The Mid-Pleistocene Transition (MPT, 1,200-600 ka) marks the rapid expansion of Northern Hemisphere (NH) continental ice sheets and stronger precession pacing of glacial/interglacial cyclicity. Here, we investigate the relationship between thermocline depth in the central North Atlantic, subsurface northward heat transport and the initiation of the 100-kyr cyclicity during the MPT. To reconstruct deep-thermocline temperatures, we generated a Mg/Ca-based temperature record of deep-dwelling (similar to 800 m) planktonic foraminifera from mid-latitude North Atlantic at Site U1313. This record shows phases of pronounced heat accumulation at subsurface levels during the mid-MPT glacial driven by increased outflow of the Mediterranean Sea. Concurrent warming of the subtropical thermocline and subpolar surface waters indicates enhanced (subsurface) inter-gyre transport of warm water to the subpolar North Atlantic, which provided moisture for ice-sheet growth. Precession-modulated variability in the northward transport of subtropical waters imprinted this orbital cyclicity into NH ice-sheets after Marine Isotope Stage 24.