J. Alvarez-Solas et al., Nature Geosci., Links between ocean temperature and iceberg discharge during Heinrich events

Nature Geoscience, 3 (2010) 122-126; published online 24 January 2010; doi: 10.1038/ngeo752

Links between ocean temperature and iceberg discharge during Heinrich events

Jorge Alvarez-Solas^*,1, Sylvie Charbit¹, Catherine Ritz², Didier Paillard¹, Gilles Ramstein¹ and Christophe Dumas¹

Abstract

Palaeoclimate records have revealed the presence of millennial-scale climate oscillations throughout the last glacial period¹. Six periods of extreme cooling in the Northern Hemisphere—known as Heinrich events—were marked by an enhanced discharge of icebergs into the North Atlantic Ocean^{2, 3}, increasing the deposition of ice-rafted debris². Increased sliding at the base of ice sheets as a result of basal warming has been proposed to explain the iceberg pulses^{4, 5, 6}, but recent observations^{7, 8} suggest that iceberg discharge is related to a strong coupling between ice sheets, ice shelves and ocean conditions. Here we use a conceptual numerical model to simulate the effect of ocean temperature on ice-shelf width, as well as the impact of the resultant changes in ice-shelf geometry on ice-stream velocities. Our results demonstrate that ocean temperature oscillations affect the basal melting of the ice shelf and will generate periodic pulses of iceberg discharge in an ice sheet with a fringing shelf. We also find that the irregular occurrence of Heinrich events seen in the palaeoclimate records can be simulated by periodic ocean forcing combined with varying accumulation rates of the ice sheet. Our model simulations support a link between millennial-scale ocean temperature variability and Heinrich events during the last glacial period.

1. LSCE-CEA-CNRS, Laboratoire des Sciences du Climat et de l’Environnement, L’Orme des Merisiers, Gif sur Yvette, 91191, France
2. LGGE, Laboratoire de Glaciologie et Géophysique de l’Environnement CNRS/Université Joseph Fourier—Grenoble 1, LGGE, BP 96, 38402 Grenoble, France

*Correspondence e-mail: jorge.alvarez-solas@lsce.ipsl.fr

Link to abstract:  http://www.nature.com/ngeo/journal/v3/n2/abs/ngeo752.html