A New Theory of Glacial Cycles
Much of this work has been done in collaboration with Gordon MacDonald.
Read a quick summary
If you have a fast connection, you can view a movie of the orbits
of the inner planets for the past 3 Myr.
- In January 1994, I wrote Lawrence Berkeley Laboratory Report
LBL-35655 suggesting that the standard theory of the ice ages was wrong.
I attributed the glaciations not to variations in sunlight, but instead to
accretion of cosmic dust and/or meteors.
- In 1995, a short paper Glacial cycles and
orbital inclination by me and Gordon MacDonald was published in Nature.
- At the heart of much of this work is the orbit of the earth. I have transformed
the orbital inclination and omega for the last
3 million years to the invariable plane, available in a large (warning: 132k)
- A report, Origin of the 100 kyr glacial
cycles: eccentricity or orbital inclination? discusses many of our thoughts
on the subject (as of 1996).
- Read the abstract for my invited talk
at the Fall 1996 AGU meeting.
- Our long-titled paper "Simultaneous
presence of orbital inclination and eccentricity in proxy climate records
from Ocean drilling Program Site 806," was published in GEOLOGY vol
25, pages 3-6 (1997).
- Our paper on bispectra serves as
a tutorial and description of our initial application of this method to the
mystery of the ice age cycles.
- Spectrum of 100-kyr glacial cycle: Orbital inclination,
not eccentricity, was published in the Proc. Natl. Acad. Sci. USA, Vol
94, pp 8329-8334 (August 1997). This articles includes details of the coordinate
transformation from the zodiacal plane to the invariable plane.
- Glacial Cycles and Astronomical Forcing,
published in Science vol 277, pp 215-218 (11 July 1997). Argues that the ice
ages are astronomical in cause (without invoking the Milankovitch model),
and that insolation is not responsible for the 100 kyr cycle which dominated
for the last million years.
- Ice Ages and Astronomical Causes, a text meant
for graduate students and Ph.D.s interested in the driving force for glacial
cycles, with emphasis on the spectral analysis of global ice proxies.
Click to read the Table
of Contents, the Preface or
Chapter 1, which contains brief introductions to the History
of Climate, Ice Age Theories,
and Spectra. It can be ordered
New York, Springer
Germany, and from Amazon
in the UK.
There have been several popular articles about our work, including:
- San Francisco Chronicle news
article, by science journalist Charles Petit, appeared on Jan. 16, 1996.
- A long article about our ice age
work (and other things), written by
Robert Hurwitt (the Drama Critic for the SF Examiner) appeared in the July
19 East Bay Express.
- An update of the status of the theory, and the reactions of others, in the
October 4, 1997 issue of Science News. You can read selected excerpts
from this article.
If you would like to see what the glaciers look like today, you can view of
photo of the Greenland glaciers taken