A 125-ka record of northern South American precipitation and the role of high-to-low latitude teleconnections. (15th October 2021)

• Record Type: Journal Article
• Authors: Zhuravleva, A.; Hüls, M.; Tiedemann, R.; Bauch, H.A.
• Is Part Of: Quaternary science reviews. Volume 270(2021)
• Publication Date: 2021-10-15
• Subjects: South America -- ITCZ -- Orinoco River -- Amazon River -- Climate teleconnections -- Dansgaard-Oeschger cycles; Geology, Stratigraphic -- Quaternary -- Periodicals; Stratigraphie -- Quaternaire -- Périodiques; 551.79
• DOI: 10.1016/j.quascirev.2021.107159
• Languages: English
• ISSNs: 0277-3791

Abstract

Abstract: The occurrence of rapid last glacial temperature shifts in both Greenland ice and subpolar marine sediment cores, so-called Dansgaard-Oeschger (D-O) cycles, is evidence of a tight regional climate connectivity in these northern latitudes. By contrast, processes behind high-to-low-latitude teleconnections during the D-O cycles are less well understood, due to imprecisions in cross-dating marine and ice core records and a general lack of solid multi-proxy records from the tropical region. Here we aim to study the response of the tropical ocean-atmosphere system to D-O variability by using a sediment core from the southern Caribbean Sea, located under the direct influence of the Intertropical Convergence Zone (ITCZ) and the Atlantic meridional overturning circulation (AMOC). During D-O cycles, abrupt shifts in the deposition of fine-grained terrigenous material sourced from the Orinoco and Amazon rivers are recognized. These sedimentary changes were associated with fluctuations in both the ITCZ location and the AMOC strength through their respective influence on the hydroclimate of northern South America and strength of ocean currents delivering fluvial material to the study site. Stable oxygen isotope data further suggest increase in the upper ocean temperatures in the southeastern Caribbean Sea during stadial events. As these warming trends correlate with Antarctic temperatures, they seem to contain imprints of the bipolar seesaw and AMOC variability, demonstrating that our core location was influenced by processes prevalent in both hemispheres. Highlights: Lowered Orinoco River sediment discharge during stadials due to more arid conditions in northern South America. Reduced supply of Amazonian sediments to the SE Caribbean during stadials due to reorganization of ocean surface currents. SE Caribbean Sea warmed during cold Greenland stadials due to AMOC changes and the bipolar seesaw.