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Climate of the Past An interactive open-access journal of the European Geosciences Union
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Volume 14, issue 10
Clim. Past, 14, 1405-1415, 2018
https://doi.org/10.5194/cp-14-1405-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Clim. Past, 14, 1405-1415, 2018
https://doi.org/10.5194/cp-14-1405-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 08 Oct 2018

Research article | 08 Oct 2018

Ice core evidence for decoupling between midlatitude atmospheric water cycle and Greenland temperature during the last deglaciation

Amaëlle Landais1, Emilie Capron2,3, Valérie Masson-Delmotte1, Samuel Toucanne4, Rachael Rhodes5, Trevor Popp2, Bo Vinther2, Bénédicte Minster1, and Frédéric Prié1 Amaëlle Landais et al.
  • 1Laboratoire des Sciences du Climat et de l'Environnement, IPSL, UMR 8212, CEA-CNRS-UVSQ-UPS, Gif sur Yvette, France
  • 2Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2900, Copenhagen, Denmark
  • 3British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
  • 4IFREMER, Laboratoire Géophysique et enregistrement Sédimentaire, CS 10070, 29280 Plouzané, France
  • 5Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, UK

Abstract. The last deglaciation represents the most recent example of natural global warming associated with large-scale climate changes. In addition to the long-term global temperature increase, the last deglaciation onset is punctuated by a sequence of abrupt changes in the Northern Hemisphere. Such interplay between orbital- and millennial-scale variability is widely documented in paleoclimatic records but the underlying mechanisms are not fully understood. Limitations arise from the difficulty in constraining the sequence of events between external forcing, high- and low- latitude climate, and environmental changes.

Greenland ice cores provide sub-decadal-scale records across the last deglaciation and contain fingerprints of climate variations occurring in different regions of the Northern Hemisphere. Here, we combine new ice d-excess and 17O-excess records, tracing changes in the midlatitudes, with ice δ18O records of polar climate. Within Heinrich Stadial 1, we demonstrate a decoupling between climatic conditions in Greenland and those of the lower latitudes. While Greenland temperature remains mostly stable from 17.5 to 14.7ka, significant change in the midlatitudes of the northern Atlantic takes place at  ∼ 16.2ka, associated with warmer and wetter conditions of Greenland moisture sources. We show that this climate modification is coincident with abrupt changes in atmospheric CO2 and CH4 concentrations recorded in an Antarctic ice core. Our coherent ice core chronological framework and comparison with other paleoclimate records suggests a mechanism involving two-step freshwater fluxes in the North Atlantic associated with a southward shift of the Intertropical Convergence Zone.

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During the last glacial–interglacial climate transition (120 000 to 10 000 years before present), Greenland climate and midlatitude North Atlantic climate and water cycle vary in phase over the succession of millennial events. We identify here one notable exception to this behavior with a decoupling unambiguously identified through a combination of water isotopic tracers measured in a Greenland ice core. The midlatitude moisture source becomes warmer and wetter at 16 200 years before present.
During the last glacial–interglacial climate transition (120 000 to 10 000 years before...
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