Publication Date:
2024-01-09
Description:
We compare a new mid-Pleistocene sea surface temperature (SST) record from the eastern tropical Atlantic to changes in continental ice volume, orbital insolation, Atlantic deepwater ventilation, and Southern Ocean front positions to resolve forcing mechanisms of tropical Atlantic SST during the mid-Pleistocene transition (MPT). At the onset of the MPT, a strong tropical cooling occurred. The change from a obliquity- to a eccentricity-dominated cyclicity in the tropical SST took place at about 650 kyr BP. In orbital cycles, tropical SST changes significantly preceded continental ice-volume changes but were in phase with movements of Southern Ocean fronts. After the onset of large-amplitude 100-kyr variations, additional late glacial warming in the eastern tropical Atlantic was caused by enhanced return flow of warm waters from the western Atlantic driven by strong trade winds. Pronounced 80-kyr variations in tropical SST occurred during the MPT, in phase with and likely directly forced by transitional continental ice-volume variations. During the MPT, a prominent anomalous long-term tropical warming occurred, likely generated by extremely northward displaced Southern Ocean fronts. While the overall pattern of global climate variability during the MPT was determined by changes in mean state and frequency of continental ice volume variations, tropical Atlantic SST variations were primarily driven by early changes in Subantarctic sea-ice extent and coupled Southern Ocean frontal positions.
Keywords:
175-1077B; AGE; Alkenone, unsaturation index UK'37; Benguela Current, South Atlantic Ocean; Calculated from C37 alkenones (Brassell et al., 1986); Calculated from C37 alkenones (Prahl & Wakeham, 1987); Center for Marine Environmental Sciences; Depth, composite; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Intercore correlation; Joides Resolution; Leg175; MARUM; Ocean Drilling Program; ODP; Sample code/label; Sea surface temperature, annual mean
Type:
Dataset
Format:
text/tab-separated-values, 856 data points
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