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.

Supplement to: Bahr, André; Kaboth, Stefanie; Jiménez-Espejo, Francisco Jose; Sierro, Francisco Javier; Voelker, Antje H L; Lourens, Lucas Joost; Röhl, Ursula; Reichart, Gert-Jan; Escutia, Carlota; Hernandéz-Molina, Francisco Javier; Pross, Jörg; Friedrich, Oliver (2015): Persistent monsoonal forcing of Mediterranean Outflow Water dynamics during the late Pleistocene. Geology, 43(11), 951-954