Enhanced surface melting of the Fennoscandian Ice Sheetduring periods of North Atlantic cooling

Type Article
Date 2019-07
Language English
Author(s) Boswell Steven M.1, 2, Toucanne SamuelORCID3, Pitel-Roudaut MathildeORCID3, Creyts Timothy T.1, Eynaud Frédérique4, Bayon Germain3
Affiliation(s) 1 : Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964, USA
2 : Department of Earth and Environmental Sciences, Columbia University, New York, New York 10027, USA
3 : Institut Français de Recherche pour l’Exploitation de la Mer (IFREMER), Unité de Recherche Géosciences Marines, F-29280 Plouzané, France
4 : Laboratoire Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), UMR 5805, Université de Bordeaux, F-33615 Pessac, France
Source Geology (0091-7613) (Geological Society of America), 2019-07 , Vol. 47 , N. 7 , P. 664-668
DOI 10.1130/G46370.1
WOS© Times Cited 14

Heinrich events (HEs) are dramatic episodes of marine-terminating ice discharge and sediment rafting during periods of cold North Atlantic climate. However, the causal chain of events leading to their occurrence is unresolved. Here, we demonstrate that enhanced surface melting of land-terminating margins of the southern Fennoscandian Ice Sheet (FIS) is a recurring feature of Heinrich stadials (HSs), the cold periods during which HEs occur. We use neodymium isotopes to show that the Channel River transported detrital sediments from the interior of eastern Europe to the Bay of Biscay in the northeast Atlantic Ocean at ca. 158–154 ka. Based on similar evidence from the last glacial period, we infer that this interval corresponds to the melting and retreat of the southern FIS margin despite contemporaneous cooling in the North Atlantic and central Europe. The FIS melting episode occurred just prior to a HE, consistent with findings from the more recent HSs 1, 2, and 3. Based on this evidence, we clarify a sequence of events that precedes HEs. Precursor melting of North Atlantic–adjacent ice sheets induces an initial Atlantic meridional overturning circulation (AMOC) slowdown. Atmospheric changes during the resulting HS cause summertime warming in northern Europe that drives enhanced FIS melting. Subsequent meltwater discharge to the North Atlantic further weakens the AMOC and warms the intermediate water masses that contribute to HEs.

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Boswell Steven M., Toucanne Samuel, Pitel-Roudaut Mathilde, Creyts Timothy T., Eynaud Frédérique, Bayon Germain (2019). Enhanced surface melting of the Fennoscandian Ice Sheetduring periods of North Atlantic cooling. Geology, 47(7), 664-668. Publisher's official version : https://doi.org/10.1130/G46370.1 , Open Access version : https://archimer.ifremer.fr/doc/00499/61065/