Persistent monsoonal forcing of mediterranean outflow water dynamics during the late Pleistocene

• Main Authors: Bahr, A., Kaboth, S., Jiménez-Espejo, F. J., Sierro, F. J., Voelker, A. H L, Lourens, L., Röhl, U., Reichart, G. J., Escutia, C., Hernández-Molina, F. J., Pross, J., Friedrich, O.
• Other Authors: Stratigraphy and paleontology, NWO-VICI: Evolution of astronomically paced climate changes from Greenhouse to Icehouse world
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2015
• Subjects: Geology; North Atlantic
• Online Access: https://dspace.library.uu.nl/handle/1874/329857

The mode and vigor of the global oceanic circulation critically depend on the salinity of (sub)surface water masses advected to the loci of deep-water formation. Within the Atlantic meridional overturning circulation (AMOC), an important supplier of high-salinity waters is the Mediterranean Outflow Water (MOW), discharging into the North Atlantic via the Strait of Gibraltar. Despite its importance for the North Atlantic salinity budget, the long-term dynamics of MOW production have remained poorly understood. Here we present high-resolution records of bottom-current velocity from three drill sites within the Gulf of Cádiz that document a persistent low-latitude forcing of MOW flow speed over the past ~150 k.y. We demonstrate that the African monsoon is the predominant driver of orbital-scale MOW variability via its influence on the freshwater budget of the eastern Mediterranean Sea. Consequently, MOW formation fluctuates in concert with orbital precession overprinted by centennial-scale oscillations of high-latitude origin. We further document that Northern Hemisphere summer insolation minima stimulate maximal injection of MOW-derived salt into the North Atlantic, likely strengthening the intermediate AMOC branch. The direct coupling of MOW dynamics to low-latitude climate forcing represents a hitherto neglected process for propagating (sub)tropical climate signals into the high northern latitudes.