Vigorous exchange between the Indian and Atlantic oceans at the end of the past five glacial periods

Article

关键词: SEA-SURFACE TEMPERATURE;    SOUTH-ATLANTIC;    OVERTURNING CIRCULATION;    RECORD;    COMMUNICATION;    FLUCTUATIONS;    OCEANOGRAPHY;    SECTOR;    HEAT;   

DOI  :  10.1038/nature02785

来源: SCIE

【 摘 要 】

The magnitude of heat and salt transfer between the Indian and Atlantic oceans through 'Agulhas leakage' is considered important for balancing the global thermohaline circulation(1-3). Increases or reductions of this leakage lead to strengthening or weakening of the Atlantic meridional overturning and associated variation of North Atlantic Deep Water formation(4-6). Here we show that modern Agulhas waters, which migrate into the south Atlantic Ocean in the form of an Agulhas ring, contain a characteristic assemblage of planktic foraminifera. We use this assemblage as a modern analogue to investigate the Agulhas leakage history over the past 550,000 years from a sediment record in the Cape basin. Our reconstruction indicates that Indian - Atlantic water exchange was highly variable: enhanced during present and past interglacials and largely reduced during glacial intervals. Coherent variability of Agulhas leakage with northern summer insolation suggests a teleconnection to the monsoon system. The onset of increased Agulhas leakage during late glacial conditions took place when glacial ice volume was maximal, suggesting a crucial role for Agulhas leakage in glacial terminations, timing of interhemispheric climate change(7) and the resulting resumption of the Atlantic meridional overturning circulation(6).

【 授权许可】

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