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.

a b s t r a c tThe upper Mediterranean Outflow Water (MOW) paleo-oceanographic history in the Gulf of Cadiz is poorly constrained due to the lack of high-resolution records that pre-date the last glaciation. Existing proxy records concentrate on MOW variability along the middle slope of the Gulf of Cadiz. Here we present a continuous high-resolution benthic foraminifera δ 18 O record from the upper MOW core at IODP Expedition 339 Site U1386 in the Gulf of Cadiz of the past 150,000 years. Based on δ 18 O, grain-size and Zr/Al variability comparison of our results with existing Mediterranean Sea (MD01-2472, MD95-2043), open ocean (LR04) and Gulf of Cadiz (MD99-2339) records we have gathered new insights into the evolution of the upper MOW core on glacial-interglacial timescales. The influence of the upper MOW at Site U1386 was strongest during MIS 5 and MIS 1. Similar δ 18 O variability can be seen in the Levantine Intermediate Water (LIW) originating from the Levantine Basin of the Eastern Mediterranean Sea. We found clear indication for a vertical shift of the MOW from the upper to the middle slope of the Gulf of Cadiz during sea level lowstands coinciding with MIS 4 and MIS 2 but also during MIS 3. Additionally, our results indicate an increased upper MOW flow correlated with Heinrich Events 7 to 10 and the Younger Dryas, and also inversely relate to precession-forced monsoonal freshwater inputs into the Eastern Mediterranean. In the context of Sapropel formation, we could not find conclusive evidence of the proposed MOW shutdown in our data.

The Gulf of Cadiz constitutes a prime area to study teleconnections between the North Atlantic Ocean and climate change in the Mediterranean realm. In particular, the highly saline Mediterranean Outflow Water (MOW) is an important modulator of the North Atlantic salt budget on intermediate water levels. However, our understanding of its paleoceanographic evolution is poorly constrained due to the lack of high‐resolution proxy records that predate the last glacial cycle. Here we present the first continuous and high‐resolution (~ 1 kyr) benthic δ18O and δ13C as well as grain size records from Integrated Ocean Drilling Program Site U1386 representing the last ~570 kyr. We find three distinct phases of MOW variability throughout the Late to Middle Pleistocene at Site U1386 associated with prominent shifts in its composition and flow strength. We attribute this long‐term variability to changes in water mass sourcing of the MOW. Superimposed on the long‐term change in water mass sourcing is the occurrence of distinct and precession paced δ18O enrichment events, which contrast the pattern of global ice volume change as inferred from the global mean δ18O signal (i.e., LR04) but mimics that of the adjacent Mediterranean Sea. We attribute these enrichment events to a profound temperature reduction and salinity increases of the MOW, aligning with similar changes in the Mediterranean source region. These events might further signify ice volume increases as inferred from significant sea level drops recorded in the Red Sea and/or increased influence of North Atlantic intermediate water masses when MOW influence was absent at Site U1386.

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