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TitleAlongflow variability of the Labrador Current during the Holocene
AuthorYang, Y; Piper, D J WORCID logo
SourceQuaternary Science Reviews vol. 267, 107110, 2021 p. 1-11,
Alt SeriesNatural Resources Canada, Contribution Series 20210081
Mediapaper; on-line; digital
File formatpdf; html
ProvinceNova Scotia; Eastern offshore region
NTS10; 11D; 20P; 21A
AreaAtlantic Ocean; Scotian Shelf
Lat/Long WENS -65.0000 -62.0000 45.0000 43.0000
Subjectsmarine geology; environmental geology; geochronology; Nature and Environment; Science and Technology; Holocene; continental margins; continental shelf; currents; current circulation; paleoclimates; water temperature; marine sediments; silts; marine sediment cores; core analysis; grain size analyses; radiometric dating; radiocarbon dating; models; Labrador Current; Emerald Basin; Atlantic Meridional Overturning Circulation; North Atlantic Oscillation; West Greenland Current; Greenland Ice Sheet; Fresh water; Climate change; Phanerozoic; Cenozoic; Quaternary
Illustrationsgeoscientific sketch maps; location maps; tables; models; time series; bar graphs; plots
ProgramMarine Geoscience for Marine Spatial Planning
Released2021 07 29
AbstractThe Labrador Current (LC) provides freshwater from the Arctic to the North Atlantic, modulating the Atlantic Meridional Overturning Circulation (AMOC), and therefore affecting the broader North Atlantic climate. The Holocene alongflow variability of the LC vigor, and the associated forcing mechanisms, are poorly understood due to the limited data near the southern limit of the LC. Here we present a new 9.4 ka record of distal LC vigor over the Scotian Shelf using the sortable-silt proxy, which allows for the first time an assessment of the alongflow changes in Holocene LC vigor and hence its forcing mechanisms. LC speed on the Scotian Shelf decreased slightly from 9.4 to 8.0 ka, during which the 8.1 ka meltwater event had a strong influence. The LC progressively intensified from 8.0 to 5.0 ka, weakened between 5.0 and 1.8 ka and gradually intensified from 1.8 to 0.5 ka. Our synthesis reveals that the Holocene flow history of the LC appears geographically variable due to the interaction of the inner and outer LC. The mean size of the sortable silt data on the Scotian Shelf involve inner or outer LC signals in different periods of the Holocene. The LC vigor on the Scotian Shelf between 9.4-8.0 ka and 1.8-0.5 ka represent the outer LC, which is consistent with the stronger West Greenland Current and increased influx of Atlantic-sourced water to the outer LC. We find a broad agreement between inner LC vigor and AMOC-related sea surface temperature (SST) of the subpolar North Atlantic and the North Atlantic Oscillation (NAO), which suggests that a strong (weak) inner LC is generally associated with regional warm (cold) climate and negative (positive) NAO. The outer LC vigor is dominated by the NAO during the Holocene and partly controlled by freshwater supply between 10.0 and 5.0 ka. We also demonstrate the negative/positive link between the inner/outer LC vigor and the NAO on a millennium time scale. This study improves our understanding of LC variability and sensitivity to anthropogenic warming, and suggest that inner (outer) LC vigor may experience not only a decreasing (increasing) trend in a future warmer climate, with additional effects resulting from enhanced melting of the Greenland ice sheet.
Summary(Plain Language Summary, not published)
The grain size of muds on the Scotian Shelf allow an estimate of the flow velocity of the Labrador Current over the past 9000 years. This record is compared with similar records from the Labrador Shelf and Grand Banks. It provides insights on future changes in the Labrador Current as a result of global warming.

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