[A-CC26] Ice cores and paleoenvironmental modeling

[ACC26-P05] The effect of ocean circulation on glacial-interglacial cycles

*Ryotaro Todoroki¹, Ayako Abe-Ouchi¹, Fuyuki SAITO², Takashi Obase¹, Wing-Le Chan¹, Sam Sherriff-Tadano³, Yasuto Watanabe⁴ (1.Atmosphere and Ocean Research Institute, The University of Tokyo, 2.Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 3.The University of Leeds, 4.The University of Tokyo)

Keywords:Glacial-Interglacial Cycles, Dansgaard-Oeschger Event

The climate of the Pleistocene is characterized by glacial cycles which are said to be driven by orbital forcing. On the other hand, the state of the ocean like the AMOC strength also has an important role in the earth system. For example, the AMOC is closely related to a bi-polar seesaw mechanism, not only during deglaciation, but it may also affect ice sheet extent throughout entire glacial cycle. Indeed, some recent studies showed the effect of millennial scale oscillations, namely Dansgaard-Oeschger events (DOE), on ice sheets using ice-sheet models. In this study, we use an ice-sheet model (IcIES; Abe-Ouchi et al., 2013) and introduce the effects of DOE by applying temperature anomalies from hosing experiments in GCM and NGRIP ice core δ¹⁸O data, which can be seen as an indicator of the AMOC strength. Including the effects of a DOE-like ocean circulation in the ice-sheet model, the North American ice sheet retreats to the southern margins of the Hudson Bay and the total ice volume of the North American and Eurasian ice sheets decreases to 50m (SLE) in MIS3. As for the last deglaciation, during the Bølling-Allerød (B-A) interstadial, the Northern American and Eurasian ice sheets melt rapidly in accordance with AMOC recovery and both discharge meltwater. When applying the DOE effect, meltwater from the Eurasian ice sheet increases dramatically and the amount surpasses that from the North American ice sheet during peak melting, leading to a near-complete deglaciation of the Eurasian ice sheet during the B-A warming period.