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Quaternary Science Reviews 23 (2004) 18791890 Are the 41 kyr glacial oscillations a linear response to

Summary: Quaternary Science Reviews 23 (2004) 1879≠1890
Are the 41 kyr glacial oscillations a linear response to
Milankovitch forcing?
Yosef Ashkenazya,√, Eli Tzipermanb
Environmental Sciences, Weizmann Institute, Rehovot 76100, Israel
Department of Earth and Planetary Sciences and Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
Received 7 January 2004; accepted 20 April 2004
The characteristics of glacial oscillations changed drastically $ 0:8 Ma ago, at the ``mid-Pleistocene transition''. During the past
0.8 Ma the $ 100 kyr glacial≠interglacial oscillations were strongly asymmetric (i.e., long glacial intervals of growth followed by
rapid intervals of deglaciation). The 40 kyr oscillations prior to the mid-Pleistocene transition were of a smaller amplitude and less-
asymmetrical looking. The smaller amplitude, apparently symmetric form and period that matches that of obliquity, suggests that
these oscillations were a linear response to Milankovitch forcing, while the 100 kyr oscillations are attributed either to some
nonlinear self-sustained variability due to a mechanism internal to the climate system itself or to nonlinear amplification of the
insolation forcing. The significant strengthening of the 100 kyr eccentricity power in the past $ 800 kyr is one of the intriguing
questions of climate history.
Here we show that glacial≠interglacial oscillations pre-mid-Pleistocene transition are, in fact, significantly asymmetric. This
asymmetry may contradict a straight forward linear Milankovitch explanation, and we therefore suggest that the glacial oscillations


Source: Ashkenazy, Yossi "Yosef" - Department of Solar Energy and Environmental Physics, Jacob Blaustein Institutes for Desert Research,Ben-Gurion University of the Negev
Tziperman, Eli - Departments of Earth and Planetary Sciences & School of Engineering and Applied Sciences, Harvard University


Collections: Environmental Management and Restoration Technologies; Environmental Sciences and Ecology; Geosciences; Physics