Heinrich Events

Session 6: Were all Heinrich Events the same?

Session Description

This will draw upon evidence from studies of Heinrich Events from beyond the Last Glacial Cycle to address the question as to whether all Heinrich events were the same.

Session Talks
Keynote

Beyond the tip of the iceberg: Heinrich(-like) Events during the Pleistocene

David Naafs

B.D.A. Naafs1,2*, J. Hefter1, R. Stein1, P. Ferretti3,4, S. Zhang5, and G.H. Haug2,6


1Alfred Wegener Institute for Polar and Marine Research, Department of Marine Geology and Paleontology, D-27568 Bremerhaven, Germany

2Leibniz Center for Earth Surface and Climate Studies, Institute for Geosciences, Potsdam University, D-14476 Potsdam, Germany

3CNR-IDPA Institute for the Dynamics of Environmental Processes and Department of Environmental Sciences, Informatics and Statistics, University Ca' Foscari of Venice, I-30123 Venice, Italy

4The Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, United Kingdom

5Canada-Nunavut Geosciences Office, Iqaluit NU X0A 0H0, Canada

6Geological Institute, ETH Zürich, 8092 Zürich, Switzerland


*Correspondence: David Naafs


Heinrich Events are one of the most dramatic examples of abrupt/millennial-scale climate variability that characterized the last glacial (e.g., Heinrich, 1988; Bond et al., 1992; Broecker et al., 1992) and as such have been a major research focus for the paleoceanographic community (see review in Hemming, 2004). During Hudson Strait (HS) Heinrich Events (H1, 2, 4, and 5) part of the Laurentide ice sheet collapsed, sending massive amounts of iceberg through the Hudson Strait into the Labrador Sea and North Atlantic. Although most attention is paid to the Heinrich Events of the last glacial, with the drilling of new long and continuous high-resolution records from the North Atlantic (e.g., ODP Leg 162 and IODP Leg 303/306) it has become apparent that millennial-scale ice-rafting events are an integral part of Pleistocene climate (e.g., Oppo et al., 1998; Raymo et al., 1998; McManus et al., 1999; Hodell et al., 2008; Stein et al., 2009; Bailey et al., 2010; Bolton et al., 2010; Naafs et al., 2011). However, whether these ice-rafting events represent Heinrich(-like) Events remains controversial as the source of these ice-rafting events is often poorly constrained. The identification of Heinrich(-like) Events during older glacials is important as it can provide information about the processes, mechanisms, and necessary boundary conditions needed for Heinrich Events, which are still poorly understood.

In this context, here we review and discuss the occurrence of ice-rafting events in the mid-latitude North Atlantic during the entire Pleistocene (last 2.6 Ma). Using a combination of organic and inorganic source-indicators and several IODP Sites here we demonstrate that HS Heinrich(-like) Events are limited to the last 640 ka (MIS 16) (Hodell et al., 2008; Stein et al., 2009; Naafs et al., 2011). We were able to pinpoint a specific rock formation (Zhang, 2008) contributing to the organic fraction of ice-rafted debris (IRD) in HS Heinrich Layers and show that this source was identical for each HS Heinrich(-like) Events of the last 640 ka. This suggests that the Laurentide ice sheet had a similar configuration during the last 7 glacials, but was unable to generate massive ice-rafting events prior to MIS 16. Thus, although millennial-scale ice-rafting events were an integral part of Quaternary climate, HS Heinrich(-like) Events that involved instability of the Laurentide ice sheet were restricted to the last 640 ka. Their first occurrence is most likely related to a change in Laurentide ice sheet dynamics with a larger (volume) Laurentide ice sheet that was able to generate massive calving events for the first developing during MIS 16 (Hodell et al., 2008), in-line with modeled Laurentide ice sheet volume (Bintanja and van de Wal, 2008). These results highlight the importance of IRD source indicators in long-term records as well as the role of the Laurentide ice sheet in the Mid-Pleistocene Transition that ended with MIS 16 and the appearance of the 100-ka world (Clark et al., 2006).


References

Bailey, I., Bolton, C.T., DeConto, R.M., Pollard, D., Schiebel, R., et al., 2010. A low threshold for North Atlantic ice rafting from "low?slung slippery" late Pliocene ice sheets. Paleoceanography 25 (1), p. PA1212. doi: 10.1029/2009pa001736

Bintanja, R., van de Wal, R.S.W., 2008. North American ice-sheet dynamics and the onset of 100,000-year glacial cycles. Nature 454 (7206), pp. 869-872. doi: 10.1038/nature07158

Bolton, C.T., Wilson, P.A., Bailey, I., Friedrich, O., Beer, C.J., et al., 2010. Millennial-scale climate variability in the subpolar North Atlantic Ocean during the late Pliocene. Paleoceanography 25, p. PA4218. doi: 10.1029/2010PA001951

Bond, G., Heinrich, H., Broecker, W., Labeyrie, L., McManus, J., et al., 1992. Evidence for massive discharges of icebergs into the North Atlantic ocean during the last glacial period. Nature 360 (6401), pp. 245-249

Broecker, W., Bond, G., Klas, M., Clark, E., McManus, J., 1992. Origin of the northern Atlantic's Heinrich events. Climate Dynamics 6 (3), pp. 265-273. doi: 10.1007/BF00193540

Clark, P.U., Archer, D., Pollard, D., Blum, J.D., Rial, J.A., et al., 2006. The middle Pleistocene transition: characteristics, mechanisms, and implications for long-term changes in atmospheric pCO2. Quaternary Science Reviews 25 (23-24), pp. 3150-3184. doi: 10.1016/j.quascirev.2006.07.008

Heinrich, H., 1988. Origin and consequences of cyclic ice rafting in the Northeast Atlantic Ocean during the past 130,000 years. Quaternary Research 29 (2), pp. 142-152. doi: 10.1016/0033-5894(88)90057-9

Hemming, S.R., 2004. Heinrich events: Massive late Pleistocene detritus layers of the North Atlantic and their global climate imprint. Review of Geophysics 42 (1), p. RG1005. doi: 10.1029/2003rg000128

Hodell, D.A., Channell, J.E.T., Curtis, J.H., Romero, O.E., Röhl, U., 2008. Onset of "Hudson Strait" Heinrich events in the eastern North Atlantic at the end of the middle Pleistocene transition (~640 ka)? Paleoceanography 23, p. PA4218. doi: 10.1029/2008PA001591

McManus, J.F., Oppo, D.W., Cullen, J.L., 1999. A 0.5-Million-Year Record of Millennial-Scale Climate Variability in the North Atlantic. Science 283 (5404), pp. 971-975. doi: 10.1126/science.283.5404.971

Naafs, B.D.A., Hefter, J., Ferretti, P., Stein, R., Haug, G.H., 2011. Sea surface temperatures did not control the first occurrence of Hudson Strait Heinrich Events during MIS 16. Paleoceanography 26, p. PA4201. doi: 10.1029/2011PA002135

Oppo, D.W., McManus, J.F., Cullen, J.L., 1998. Abrupt Climate Events 500,000 to 340,000 Years Ago: Evidence from Subpolar North Atlantic Sediments. Science 279 (5355), pp. 1335-1338. doi: 10.1126/science.279.5355.1335

Raymo, M.E., Ganley, K., Carter, S., Oppo, D.W., McManus, J., 1998. Millennial-scale climate instability during the early Pleistocene epoch. Nature 392 (6677), pp. 699-702. doi: 10.1038/33658

Stein, R., Hefter, J., Grützner, J., Voelker, A., Naafs, B.D.A., 2009. Variability of surface-water characteristics and Heinrich-like Events in the Pleistocene mid-latitude North Atlantic Ocean: Biomarker and XRD records from IODP Site U1313 (MIS 16-9). Paleoceanography 24, p. PA2203. doi: 10.1029/2008PA001639

Zhang, S., 2008. New insights into Ordovician oil shales in Hudson Bay Basin: their number, stratigraphic position, and petroleum potential. Bulletin of Canadian Petroleum Geology 56 (4), pp. 300-324. doi: 10.2113/gscpgbull.56.4.300

Dr. Jennifer D. Stanford, Geography & Environment, University of Southampton