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Thornalley, David JR; Oppo, Delia W; Ortega, Pablo; Robson, Jon I; Brierley, Chris M; Davis, Renee; Hall, Ian R; Moffa-Sanchez, Paola; Rose, Neil L; Spooner, Peter T; Yashayaev, Igor M; Keigwin, Lloyd D (2019): Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years. Woods Hole Oceanographic Institution, Department of Geology & Geophysics, PANGAEA, https://doi.org/10.1594/PANGAEA.902495, Supplement to: Thornalley, DJR et al. (2018): Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years. Nature, 556(7700), 227-230, https://doi.org/10.1038/s41586-018-0007-4

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Abstract:
The Atlantic meridional overturning circulation (AMOC) is a system of ocean currents that has an essential role in Earth's climate, redistributing heat and influencing the carbon cycle. The AMOC has been shown to be weakening in recent years1; this decline may reflect decadal-scale variability in convection in the Labrador Sea, but short observational datasets preclude a longer-term perspective on the modern state and variability of Labrador Sea convection and the AMOC. Here we provide several lines of palaeo-oceanographic evidence that Labrador Sea deep convection and the AMOC have been anomalously weak over the past 150 years or so (since the end of the Little Ice Age, LIA, approximately AD 1850) compared with the preceding 1,500 years. Our palaeoclimate reconstructions indicate that the transition occurred either as a predominantly abrupt shift towards the end of the LIA, or as a more gradual, continued decline over the past 150 years; this ambiguity probably arises from non-AMOC influences on the various proxies or from the different sensitivities of these proxies to individual components of the AMOC. We suggest that enhanced freshwater fluxes from the Arctic and Nordic seas towards the end of the LIA—sourced from melting glaciers and thickened sea ice that developed earlier in the LIA—weakened Labrador Sea convection and the AMOC. The lack of a subsequent recovery may have resulted from hysteresis or from twentieth-century melting of the Greenland Ice Sheet. Our results suggest that recent decadal variability in Labrador Sea convection and the AMOC has occurred during an atypical, weak background state. Future work should aim to constrain the roles of internal climate variability and early anthropogenic forcing in the AMOC weakening described here. The data presented here is the supporting data for Thornalley et al. 2018 (see details below) and is derived from cores KNR-178-56JPC and KNR-178-48JPC. It includes the mean sortable silt size, details of radiocarbon dating, the % nps and binned sub-surface temperature reconstructions.
Keyword(s):
Atlantic meridional overturning circulation; deep water formation; sortable silt; subsurface ocean temperatures
Coverage:
Median Latitude: 42.371575 * Median Longitude: -63.934354 * South-bound Latitude: 35.466667 * West-bound Longitude: -74.716667 * North-bound Latitude: 55.000000 * East-bound Longitude: -54.816667
Size:
22 datasets

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Datasets listed in this publication series

  1. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): 210Pb dating from sediment core KNR178-56JPC. https://doi.org/10.1594/PANGAEA.902489
  2. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Age analysis from sediment core KNR158-4-MC10. https://doi.org/10.1594/PANGAEA.902476
  3. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Age analysis from sediment core KNR178-48JPC. https://doi.org/10.1594/PANGAEA.902483
  4. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Age analysis from sediment core KNR178-56JPC. https://doi.org/10.1594/PANGAEA.902486
  5. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Age analysis from sediment core OCE326-MC29D. https://doi.org/10.1594/PANGAEA.902481
  6. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Age and SPG UOHC in 0 - 700 m. https://doi.org/10.1594/PANGAEA.902491
  7. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Alternate binning ages (year CE) are mid-point of bin interval. https://doi.org/10.1594/PANGAEA.902493
  8. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Density and age analysis from Central Labrador Sea. https://doi.org/10.1594/PANGAEA.902456
  9. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Lead 210 activity from sediment core KNR178-56JPC. https://doi.org/10.1594/PANGAEA.902490
  10. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Neogloboquadrina pachyderma and age analysis from sediment core KNR158-4-MC10. https://doi.org/10.1594/PANGAEA.902460
  11. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Neogloboquadrina pachyderma and age analysis from sediment core OCE32-MC13A. https://doi.org/10.1594/PANGAEA.902462
  12. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Neogloboquadrina pachyderma and age analysis from sediment core OCE32-MC25A. https://doi.org/10.1594/PANGAEA.902463
  13. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Neogloboquadrina pachyderma and age analysis from sediment core OCE32-MC29D. https://doi.org/10.1594/PANGAEA.902461
  14. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Reconstructed water temperature and Salinity fom the north east Labrador Sea. https://doi.org/10.1594/PANGAEA.902459
  15. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Silt and age analysis from sediment core KNP178-56JPC. https://doi.org/10.1594/PANGAEA.902449
  16. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Silt and age analysis from sediment core KNR-178-48JPC. https://doi.org/10.1594/PANGAEA.902454
  17. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Spheroidal carbonaceous particle from sediment core KNR158-4-MC10. https://doi.org/10.1594/PANGAEA.902471
  18. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Spheroidal carbonaceous particle from sediment core KNR178-48JPC. https://doi.org/10.1594/PANGAEA.902468
  19. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Spheroidal carbonaceous particle from sediment core KNR178-56JPC. https://doi.org/10.1594/PANGAEA.902465
  20. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Spheroidal carbonaceous particle from sediment core OCE326-MC29D. https://doi.org/10.1594/PANGAEA.902469
  21. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Temperature sub AMOC fingerprints using the EN4 dataset. https://doi.org/10.1594/PANGAEA.902494
  22. Thornalley, DJR; Oppo, DW; Ortega, P et al. (2019): Temperature sub stacks analysis. https://doi.org/10.1594/PANGAEA.902492