Labrador Sea Water variability over the last 3000 years

English Abstract:

 The Labrador Sea is a key location for the Earth's climate system, because it is a major component of the Atlantic meridional overturning circulation (AMOC). Due to intense surface air–sea heat exchange, dense ocean mixed layers are created, forming Labrador Sea Water (LSW), which ventilates the intermediate depths of the North Atlantic and beyond. Various studies have revealed considerable spatial and temporal variability, associated with the formation and meridional transport of this water mass, over the past few decades. Yet, crucially, because of the limited temporal extent of the instrumental records, its longer-term history and interactions with the climate at multidecadal to centennial time-scales remains limited.

In this study, we present new multi-proxy records including sortable silt and foraminiferal assemblage counts and stable istotopes from decadally resolved marine sediment cores recovered from the Eirik (SE Greenland) and Gardar (S. Iceland) Drifts to infer hydrographic changes in the LSW and thus better understand the role that the ocean played in the centennial climate variability over the late Holocene. Our results show coherent changes between the records and suggest a decrease in the formation of LSW with similar timing to the cold periods that have been previously recorded as glacial advances in the circum-North Atlantic at 3000-2500; 1100-1500 and 500-100 yrs BP. These findings strongly indicate that hydrographic changes in the Labrador Sea and the associated variability in LSW formation rates may have played an active role in these climate anomalies.