Evidence of cooling in the tropical South Atlantic off southeastern Brazil during the last 50 kyr

Abstract

The tropical Atlantic has been considered as a huge energy source, contributing to the tremendous heat and moisture that can be delivered from the equatorial region towards the high latitudes through ocean current circulation. However, there is still debate whether the cold waters from the south ever had an influence on the tropical Atlantic off southeastern Brazil during glacial times. This study aims to reconstruct the tropical Atlantic environmental conditions off southeastern Brazil, to investigate whether this area had been influenced by cold waters from the south during the last glacial maximum (LGM), and to correlate the marine environmental changes with the climate and vegetation changes on the continent. This study provides the first long dinocyst record off southeastern Brazil of the last ca. 50 kyr. In combination with the freshwater algae and pollen records, it contributes to a better understanding of marine and terrestrial environmental changes in tropical regions of southeastern Brazil. The study indicates a relatively low sea surface temperature (SST), more eutrophic and unstable sea surface conditions in tropical South Atlantic off southeastern Brazil from 50 to 45 cal kyr BP. From 45 to 25 cal kyr BP, SST was relatively high, stable and less eutrophic conditions occurred, indicating a stable influence by the Brazil Current (BC). From 25 to 12 cal kyr BP, in particular during the LGM, SST decreased markedly, suggesting the occurrence of colder water masses from the south. Since the Lateglacial, SST increased and became relatively stable.