Ice core evidence for decoupling between midlatitude atmospheric water cycle and Greenland temperature during the last deglaciation
|Author(s)||Landais Amaelle1, Capron Emilie2, 3, Masson-Delmotte Valerie1, Toucanne Samuel4, Rhodes Rachael5, Popp Trevor2, Vinther Bo2, Minster Benedicte1, Prie Frederic1|
|Affiliation(s)||1 : CEA CNRS UVSQ UPS, Lab Sci Climat & Environm, IPSL, UMR 8212, Gif Sur Yvette, France.
2 : Univ Copenhagen, Ctr Ice & Climate, Niels Bohr Inst, Juliane Maries Vej 30, DK-2900 Copenhagen, Denmark.
3 : British Antarctic Survey, Madingley Rd, Cambridge CB3 0ET, England.
4 : IFREMER, Lab Geophys & Enregistrement Sedimentaire, CS 10070, F-29280 Plouzane, France.
5 : Univ Cambridge, Dept Earth Sci, Downing St, Cambridge CB2 3EQ, England.
|Source||Climate Of The Past (1814-9324) (Copernicus Gesellschaft Mbh), 2018-10 , Vol. 14 , N. 10 , P. 1405-1415|
|WOS© Times Cited||17|
The last deglaciation represents the most recent example of natural global warming associated with largescale 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 O-17-excess records, tracing changes in the midlatitudes, with ice delta O-18 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 14.7 ka, significant change in the midlatitudes of the northern Atlantic takes place at similar to 16:2 ka, 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.