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Glacial isostatic adjustment-based refinements of deglaciation history: the case of Heinrich event 1 and the “Mystery Interval”

Event Type: 
Seminar
Event Date: 
13 November 2018 - 4:00pm to 5:00pm
Venue: 
ASE 3D Viz Laboratory Room (N2-B1c-16c)
Speaker: 
Richard Peltier
About the speaker: 

Richard Peltier is currently University Professor and Professor of Physics at the University of Toronto from which he received his doctoral degree in the same subject. He also holds an honorary doctoral degree from the University of Waterloo. Wikepedia lists all of his distinctions.  In 2004 he shared, with Nick Shackleton, the Vetlesen Prize in Earth Science from the Vetlesen Foundation of New York and in 2010 was the recipient of the Bower Award and Prize of the Franklin Institute of Philadelphia for his research on “Earth Systems”. In 2012, he won the Gerhard Hertzberg Canada Gold Medal in Science and Engineering, Canada’s highest scientific award, and in the following year the Killam Prize in Natural Science of the Canada Council for the Arts. He is the Director of the Centre for Global Change Science at the university of Toronto and Scientific Director of the SciNet high performance computing facility, the leading facility of this kind in Canada.

About the event: 

Important contributions have been made to the understanding of Quaternary climate variability thro ugh application of the formalism that has been developed to understand the glacial isostatic adjustment process. Nevertheless there remain significant issues concerning the nature of ice-earth-ocean interactions in regions in which ice on the periphery of continental ice sheets is initially grounded below sea level. One such region that has been the focus of recent research consists of the Ross Sea and Weddell Sea embayments of Antarctica. More important, but much less well understood, are issues surrounding the ice streams through which the Laurentide ice sheet of North America interacted with the oceans during the glaciation-deglaciation process. An especially important example of this interaction is that which involved the Hudson Strait ice stream which, during both Marine Isotope Stage 3 (MIS3) and during the deglaciation process, became intensely unstable. Such instabilities were responsible for the so-called Heinrich Events, which were themselves the cause of the millennium timescale Dansgaard-Oeschger oscillations which dominated climate variability during MIS3 but also during deglaciation. The most recent Heinrich event, referred to as H1 and which began approximately 16,800 years ago, was ultimately responsible for the Bolling-Allerod warming event and meltwater pulse 1A in the Barbados record of deglacial sea level history. I will discuss ongoing work directed towards the development of a rigorous theory of Heinrich events. This begins with the demonstration that radiocarbon dated relative sea level histories can be employed to unambiguously demonstrate that Heinrich events do involve instability of the Hudson Strait ice stream. I will then discuss the physical mechanisms that control the approximately 7000 year repeat time between successive such events in MIS3 as well as the forcing by the M2 tide which appears to be responsible for the initiation of instability.