The paleoclimate and the climate community has adopted a Quaternary Ice Age model in which the primary climate driver is the Milankovitch eccentricity cycle (MEC).   But in the figure below, which I adapted in 2012 (1) from Roe 2006 (2), it was certainly hard for me to see any visual correlation between the ~100K year glacial oscillation (inferred Temperature, cyan) and the MEC (orbital, magenta).  Subsequent correlation work on my part (informal, unpublished) supports the concern that the two time series are for all practical purposes, uncorrelated.

malnkovich graph and glacial oscillations

In 2013, at a paleo conference at the NM Museum of Natural History and Science (3), I presented something that had apparently never been done (or at least published) before.  I ran an FFT on the Milankovitch combined orbital cycles (the magenta line above).  The result is shown below on the right, with the ‘true’ glacial cycle at left.

MECvsGO_2

The graph demonstrates that there is no power associated with the 100,000 year MEC, even though this cycle is asserted to be the driver for the 100,000 year glacial oscillations of the past ~1 million years.  In  some texts, that lack of power is barely acknowledged, and in a number other texts there is no mention at all of this critical deficiency.

There are many other reasons, often easily found in the scientific literature, to dismiss MEC as a climate driver.  I plan to provide further posts regarding this important misconception.

1. Wallace, M.G., 2012, The Devil’s Hole is in the  Details,  Poster presentation at  American Geophysical Union (AGU) Fall 2012 Conference, San Francisco, CA  PP51B-2133

2. Roe, G., 2006, “In Defense of Milankovitch”, Geophysical Research Letters, Vol. 33, L24703

3. Wallace, M.G.  and Wilgus-Hastings, C. 2013, EXPLORATION OF POSSIBLE CORRELATIONS OF THE INTERSTELLAR MEDIUM (IM) OVER TIME WITH THE CARBONIFEROUS-PERMIAN BOUNDARY New Mexico Museum of Natural History and Science, Bulletin 60

 

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