Paleoceanographic and climatic teleconnections between the subarctic and subtropical North Atlantic during the last interglacial (MIS 5e)

• Main Author: Zhuravleva, Anastasia
• Other Authors: Frank, Martin, Schiebel, Ralf
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2018
• Subjects: thesis; ddc:550; last interglacial; MIS 5e; Greenland ice sheet; AMOC; ITCZ; climatic variability; letztes Interglazial; grönländisches Eisschild; klimatische Variabilität; Greenland; East Greenland; Eisschild*; Ice Sheet; Labrador Sea; Nordic Seas; North Atlantic; Subarctic
• Online Access: https://nbn-resolving.org/urn:nbn:de:gbv:8-diss-235318; https://macau.uni-kiel.de/receive/diss_mods_00023531; https://macau.uni-kiel.de/servlets/MCRFileNodeServlet/dissertation_derivate_00007799/Zhuravleva_2017_Dissertation.pdf

The last interglacial, MIS (Marine Isotope Stage) 5e, lasting from about ~129 to 116 ka, holds important implications for the projected global warming, as this geological interval is believed to have been significantly warmer-than-preindustrial. This thesis refines the current understanding of the MIS 5e paleoceanography in the subarctic and subtropical North Atlantic, providing new insights into ice-sheets dynamics and cross-latitudinal climatic teleconnections. For this purpose, a multi-proxy dataset comprising stable isotope compositions, foraminiferal assemblages and lithic as well as X-ray fluorescence data was produced using marine sediments from the Nordic Seas and the Bahama region. Several lines of evidence from the Nordic Seas suggest a strong sea surface freshening that persisted in the region until mid-MIS 5e (~125 ka). Comparison of published data from the Labrador Sea with the new records from the East Greenland margin provides evidence for a millennial-scale sea surface cooling and reduction in vertical water convection during early MIS 5e (at ~126.5 ka), which appears to follow a meltwater discharge event attributed to the Greenland deglaciation. A multiproxy dataset from the Bahama region further reveals a comparable cooling event as found in the high northern latitudes during early MIS 5e. The cooling was associated with a sudden southward displacement of the Intertropical Convergence Zone, in relation to a temporary reduction in deep-water formation. These observations lead to the inference that the persistent high-latitude freshening and unstable deep-water overturning during early MIS 5e accounted for a particularly sensitive climatic regime, resulting in the abrupt cold-warm switches which could be traced across various oceanic basins. Die letzte Warmzeit, das interglaziale MIS (Marine Isotope Stage) 5e kann wichtige Rückschlüsse zum Verständnis der gegenwärtigen globalen Erderwärmung zulassen, da dieses geologische Intervall (Dauer von ca. ~129 bis 116 ka) durch höhere Temperaturen ...