Latitudinal Variance in the Drivers and Pacing of Warmth During Mid-Pleistocene MIS 31 in the Antarctic Zone of the Southern Ocean

• Published in: Paleoceanography and Paleoclimatology
• Main Authors: Warnock, J.P., Reilly, B.T., Raymo, M.E., Weber, M.E., Peck, V., Williams, T., Armbrecht, L., Bailey, I., Brachfeld, S., Fauth, G., García-García, M. (Margarita)
• Format: Article in Journal/Newspaper
• Language: English
• Published: Centro Oceanográfico de Cádiz 2022
• Subjects: global warming; antarctic zone; sea surface; pleistocene; sea ice; Antarctic; Scotia Sea; Southern Ocean; The Antarctic; West Antarctic Ice Sheet; Antarc*; Ice Sheet; Ice Shelf; Ice Shelves; Sea ice
• Online Access: http://hdl.handle.net/10508/15913; https://doi.org/10.1029/2021PA004394

Early Pleistocene Marine Isotope Stage (MIS)-31 (1.081–1.062 Ma) is a unique interval of extreme global warming, including evidence of a West Antarctic Ice Sheet (WAIS) collapse. Here we present a new 1,000-year resolution, spanning 1.110–1.030 Ma, diatom-based reconstruction of primary productivity, relative sea surface temperature changes, sea-ice proximity/open ocean conditions and diatom species absolute abundances during MIS-31, from the Scotia Sea (59°S) using deep-sea sediments collected during International Ocean Discovery Program (IODP) Expedition 382. The lower Jaramillo magnetic reversal (base of C1r.1n, 1.071 Ma) provides a robust and independent time-stratigraphic marker to correlate records from other drill cores in the Antarctic Zone of the Southern Ocean (AZSO). An increase in open ocean species Fragilariopsis kerguelensis in early MIS-31 at 53°S (Ocean Drilling Program Site 1,094) correlates with increased obliquity forcing, whereas at 59°S (IODP Site U1537; this study) three progressively increasing, successive peaks in the relative abundance of F. kerguelensis correlate with Southern Hemisphere-phased precession pacing. These observations reveal a complex pattern of ocean temperature change and sustained sea surface temperature increase lasting longer than a precession cycle within the Atlantic sector of the AZSO. Timing of an inferred WAIS collapse is consistent with delayed warmth (possibly driven by sea-ice dynamics) in the southern AZSO, supporting models that indicate WAIS sensitivity to local sub-ice shelf melting. Anthropogenically enhanced impingement of relatively warm water beneath the ice shelves today highlights the importance of understanding dynamic responses of the WAIS during MIS-31, a warmer than Holocene interglacial. Postprint