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TitleImpact of Medieval Climate Anomaly and Little Ice Age on the Labrador Current flow speed and the AMOC reconstructed by the sediment dynamics and biomarker proxies
AuthorRashid, HORCID logo; Zhang, Z; Piper, D J WORCID logo; Patro, R; Xu, Y
SourcePalaeogeography, Palaeoclimatology, Palaeoecology 620, 2023 p. 1-14, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20200411
Mediapaper; on-line; digital
File formatpdf
ProvinceNewfoundland and Labrador; Eastern offshore region
NTS1; 11; 10; 20; 21A; 21B; 21F; 21G; 21H; 21I; 21J; 21K; 21N; 21O; 21P; 2; 12A; 12B; 12C; 12D; 12E; 12F; 12G; 12H; 22A; 22B; 22C; 22F; 22G; 22H
Lat/Long WENS -70.0000 -45.0000 50.0000 40.0000
Subjectsenvironmental geology; geochronology; paleontology; climate; ice; offshore currents; currents; sediments; marine sediments; sedimentation dynamics; Labrador Current
Illustrationslocation maps; profiles; tables; graphs
ProgramGeoscience for Oceans Management Geohazards and Constraints to Offshore Development
Released2023 04 11
AbstractIt is widely accepted that the changes in freshwater transport into the Labrador Sea occurred during the Medieval Climate Anomaly (MCA) and Little Ice Age (LIA), which were instrumental in modifying the climate surrounding the North Atlantic. However, the extent to which paleo proxies accurately reflect freshwater transport is poorly known due simply to lack of data. This study provides the first direct proxy record of freshwater supply by the sediment dynamics sortable silt proxy for the past 1.45 ka. A sediment core MO2009061-0217 (46.387°N, 46.742°W) retrieved off the SE Grand Banks along the flow path of the Labrador Current was used to determine the sortable silt and extract lipid biomarkers. The sortable silt data were converted to current speed (cm/s), which suggests that the Labrador Current was weak during the MCA and most vigorous during the LIA. One concurrent water column temperature proxy, namely TEX86 based on glycerol dialkyl glycerol tetraethers (GDGTs), shows that the outer Labrador Current water was cooler during the LIA than the MCA. In contrast, the converse temperature changes were recorded along the inner Labrador Current, where temperature change was slight. Our data are placed with a few high-resolution (i.e., multi-decadal) published temperature data to reflect broader changes in the subpolar northwestern Atlantic. The temperature variations on the SE Grand Banks are analogous to those between northern Iceland and Greenland shelves over this period and reflect changes in the subpolar gyre geometry of the North Atlantic. We hypothesize that the heterogenous temperatures coupled to changes in the Labrador Current flow speed were modulated by subpolar ocean currents on the SE Grand Banks.
Summary(Plain Language Summary, not published)
Study of a high sedimentation rate core spanning the past 1500 years shows that variations in Labrador Current speed affect ocean temperatures in southern Flemish Pass. Study of spatial variation in ocean temperatures off Newfoundland during the Medieval Warm Period are a possible analogue for future global warming.

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