TAILIEUCHUNG - Heinrich event 1: an example of dynamical ice-sheet reaction to oceanic changes

To develop and test hypotheses about the events that occurred before, during and after the incident, we need to determine what actually happened. The only proof that an event may have occurred is if evidence of the event exists. If the object whose state was changed by the event still exists, then we can examine it for information about the event and about other objects that were causes or effects of the event. Therefore, we can make our previous evidence definition more specific and state that an object is evidence of an incident if its state was used to cause an event related to the incident. | Clim. Past 7 1297-1306 2011 7 1297 2011 doi cp-7-1297-2011 Author s 2011. CC Attribution License. Climate of the Past Heinrich event 1 an example of dynamical ice-sheet reaction to oceanic changes J. Alvarez-Solas1 2 M. Montoya1 3 C. Ritz1 4 G. Ramstein2 S. Charbit2 C. Dumas2 K. Nisancioglu5 T. Dokken5 and A. Ganopolski6 1Dpto. Astrofisicay Ciencias de la Atmosfera Universidad Complutense Madrid Spain 2LSCE IPSL CEA-CNRS-UVSQ UMR1572 CEA Saclay Gif-sur-Yvette France 3Instituto de Geociencias UCM-CSIC Facultad de Ciencias Fisicas Madrid Spain 4Laboratoire de Glaciologie et de Geophysique de l Environnement CNRS Saint Martin d Heres France 5Bjerknes Centre for Climate Research Bergen Norway 6Potsdam Institute for Climate Impact Research Potsdam Germany Received 3 May 2011 - Published in Clim. Past Discuss. 12 May 2011 Revised 19 September 2011 - Accepted 6 October 2011 - Published 29 November 2011 Abstract. 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 15kaBP 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 .

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