Climatic links between the subarctic and subtropical North Atlantic during the last interglacial (MIS 5e)

• Main Authors: Zhuravleva, Anastasia, Bauch, H. A.
• Format: Conference Object
• Language: unknown
• Published: 2018
• Subjects: North Atlantic; Subarctic
• Online Access: https://oceanrep.geomar.de/id/eprint/45260/

Model simulations and proxy data from the North Atlantic reveal a high-to-low latitude teleconnection that affects the subtropical ocean circulation via ocean-atmospheric forcing. While this climatic coupling is well-studied for the last glaciation and Termination 1, it has never been investigated for the last interglacial (MIS 5e, ~129-116 ka) with sufficient resolution. Here, we close this gap by comparing records from the subarctic deep-water formation sites with new assemblage and stable isotope data from the Bahama region, an area influenced by seasonal shifts of the Intertropical Convergence Zone (ITCZ). Our proxy records from the various oceanic basins reveal for early MIS 5e a comparable millennial-scale Younger Dryas-like cooling event (~127 ka), which can be used as an important marker allowing for a better chronostratigraphic constraint of the MIS 5e interval. In the subtropical North Atlantic, the abrupt cooling could not be reconciled with insolation forcing but is associated with a sudden southward shift of the ITCZ, the latter being linked to a short-term freshwater-related reduction in strength of the ocean overturning. These results help to disentangle the roles of different mechanisms controlling low-latitude climate across MIS 5e (insolation versus oceanic and/or atmospheric versus freshwater forcing). It leads to the conclusion that a persistent high-latitude freshening and unstable deep-water overturning during early MIS 5e accounted for a “transitional” and, therefore, particularly vulnerable climatic regime during this time period, causing the cold-warm switches akin to those observed during the last glacial termination.