The last interglacial (MIS 5e) cycle at Little Bahama Bank: A history of climate and sea-level changes

Abstract

Abstract. Shallow-water sediments of the Bahama region containing the last interglacial (MIS 5e) are ideal to investigate the region's sensitivity to past climatic and sea level changes. Here we present new faunal, isotopic and XRF-sediment core data 10 from the northern slope of the Little Bahama Bank. The results suggest that the bank top remained flooded across the last interglacial "plateau", ~129-117 ka, arguing for a relative sea level above -6 m for this time period. In addition, climatic variability, which today is closely coupled with movements of the intertropical convergence zone (ITCZ), is interpreted based on stable isotopes and foraminiferal assemblage records. During early MIS 5e, the mean annual ITCZ position moved northward in line with increased solar forcing and a recovered Atlantic Meridional Overturning Circulation (AMOC). The 15 early MIS 5e warmth peak was intersected, however, by a millennial-scale cooling event, consistent with a southward shift in the mean annual ITCZ position. This tropical shift is ascribed to the transitional climatic regime of early MIS 5e, characterized by persistent high-latitude freshening and, thereby, unstable AMOC mode. Our records from the Bahama region demonstrate that not only was there a tight relation between local sedimentation regimes and last interglacial sea level history, via the atmospheric forcing we could further infer an intra-interglacial connectivity between the polar and subtropical latitudes that 20 left its imprint also on the ocean circulation.