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An Absolute Age Scale for the Vostok Ice Core: Implications for the Role of Milankovitch Forcing of Glacial-Interglacial Climate Change
Michael Bender
Professor of Geosciences/Geochemistry
Princeton University
Faced with nearly intractable problems in radioactive decay dating of Pleistocene climate records, paleoclimatologists have developed orbital tuning timescales. In these, one takes a climate record that apparently varies with insolation, and adjusts the timescale to bring the climate changes into exact agreement with an insolation-time curve. Several papers have developed such a timescale for the Vostok ice core using depth variations in the 18O/16O ratio of O2 in the trapped gases. Strong support for this chronology comes from the record of O2/N2 in Vostok. This property is nearly constant in the atmosphere, but varies in the ice core because of gas fractionation when air is trapped in bubbles. The extent of fractionation is related to properties of ice crystals, which in turn seem to depend on insolation and the extent of snow metamorphism at the surface. The absolute chronology from this core allows us to study the relationship between climate change and insolation. We discuss Greenland and Antarctic ice core records and focus on two of the timescales they access: the long term record of northern and southern polar temperatures, and the rapid transitions from glacial to interglacial conditions at the end of 100,000 year glacial cycles.
About the Lecturer
Michael Bender received his B.S. in Chemistry at the Carnegie Institute of Technology in 1965, and his Ph.D. in Geology at Columbia University in 1970. He is currently a Professor of Geosciences at Princeton University. Additionally, he has also been a Visiting Researcher at the Centre des Faibles Raidoactivities in Yvette, France in 1983-84 and 1992-93.
Michael's research involves studies of biogeochemistry and paleoclimate. Much of the work involves measuring the changing concentration and isotopic composition of O2 in air on various timescales, and using the results to characterize the fertility of ecosystems and to study Earth's climate history. Another general area of his research interest involves measuring the concentration and isotopic composition of gases in the oceans, the troposphere, and the stratosphere in order to understand chemical reactions and physical circulation. Many aspects of this work involve the interpretation of data using simple or complex mathematical models of atmospheric circulation, climate, and large-scale biological processes.
More Information
http://geoweb.princeton.edu/people/faculty/bender/vita.html
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Michael Bender
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