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| Titel |
Heinrich event 1: an example of dynamical ice-sheet reaction to oceanic changes |
| VerfasserIn |
J. Álvarez-Solas, M. Montoya, C. Ritz, G. Ramstein, S. Charbit, C. Dumas, K. Nisancioglu, T. Dokken, A. Ganopolski |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 7, no. 4 ; Nr. 7, no. 4 (2011-11-29), S.1297-1306 |
| Datensatznummer |
250004688
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| Publikation (Nr.) |
 copernicus.org/cp-7-1297-2011.pdf |
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| Zusammenfassung |
Heinrich events, identified as enhanced ice-rafted detritus (IRD) in North Atlantic deep sea
sediments (Heinrich, 1988; Hemming, 2004) have classically been attributed to Laurentide ice-sheet
(LIS) instabilities (MacAyeal, 1993; Calov et al., 2002; Hulbe et al., 2004) and assumed to lead
to important disruptions of the Atlantic meridional overturning circulation (AMOC) and North Atlantic
deep water (NADW) formation.
However, recent paleoclimate data have revealed that most of these events probably occurred after the
AMOC had already slowed down or/and NADW largely collapsed, within about a thousand years
(Hall et al., 2006; Hemming, 2004; Jonkers et al., 2010; Roche et al., 2004), implying that the initial AMOC
reduction could not have been caused by the Heinrich events themselves.
Here we propose an alternative driving mechanism, specifically for Heinrich
event 1 (H1; 18 to 15 ka BP), by which North Atlantic ocean circulation
changes are found to have strong impacts on LIS dynamics. By combining
simulations with a coupled climate model and a three-dimensional ice sheet
model, our study illustrates how reduced NADW and AMOC weakening lead to a subsurface warming in the
Nordic and Labrador Seas resulting in rapid melting of the Hudson Strait and
Labrador ice shelves. Lack of buttressing by the ice shelves implies a
substantial ice-stream acceleration, enhanced ice-discharge and sea level
rise, with peak values 500–1500 yr after the initial AMOC reduction.
Our scenario modifies the previous paradigm of H1 by solving the paradox of
its occurrence during a cold surface period, and highlights the importance of
taking into account the effects of oceanic circulation on ice-sheets dynamics
in order to elucidate the triggering mechanism of Heinrich events. |
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