[Red Badger]

I prefer to think that it's caused by precession of the poles and wobble of the earth on it's axis...........

[ancient_geezer]

I prefer to think that it's caused by precession of the poles and wobble of the earth on it's axis...........

Hmm that that has a 27,000 yr period, unfortunately it does not fit the data.

Now the 100kyr wobble in earths orbital plain with respect to the solar system mean plane is a different matter:

 

http://newton.ex.ac.uk/aip/physnews.252.html#1

INTERPLANETARY DUST PARTICLES (IDPs) are deposited on the Earth at the rate of about 10,000 tons per year. Does this have any effect on climate? Scientists at Caltech have found that ancient samples of helium-3 (coming mostly from IDPs) in oceanic sediments exhibit a 100,000-year periodicity. The researchers assert that their data, taken along the Mid-Atlantic Ridge, support a recently enunciated idea that Earth's orbital inclination varies with a 100-kyr period; this notion in turn had been broached as an explanation for a similar periodicity in the succession of ice ages. (K.A. Farley and D.B. Patterson, Nature, 7 December 1995.)
Farley & Patterson 1998, http://www.elsevier.com/gej-ng/10/20/36/33/37/32/abstract.html
Farley http://www.gps.caltech.edu/~farley/
Farley http://www.elsevier.nl/gej-ng/10/18/23/54/21/49/abstract.html

 

http://www.publicaffairs.noaa.gov/pr96/dec96/noaa96-78.html

ABRUPT CLIMATE CHANGE DURING LAST GLACIAL PERIOD COULD BE TIED TO DUST-INDUCED REGIONAL WARMING

Preliminary new evidence suggests that periodic increases in atmospheric dust concentrations during the glacial periods of the last 100,000 years may have resulted in significant regional warming, and that this warming may have triggered the abrupt climatic changes observed in paleoclimate records, according to a scientist at the Commerce Department's National Oceanic and Atmospheric Administration. Current scientific thinking is that the dust concentrations contributed to global cooling.

 

 

 

Spectrum of 100-kyr glacial cycle: Orbital inclination, not eccentricity
Richard A. Muller^* and Gordon J. MacDonald

Origin of the 100 kyr Glacial Cycle
by Richard A. Muller

Figure 2. Spectral fingerprints in the vicinity of the 100 kyr peak: (a) for data from Site 607; (b) for data of the SPECMAP stack; (c) for a model with linear response to eccentricity, calculated from the results of Quinn et al. (ref 6); (d) for the nonlinear ice-sheet model of Imbrie and Imbrie (ref 22); and (e) for a model with linear response to the inclination of the Earth's orbit (measured with respect to the invariable plane). All calculations are for the period 0-600 ka. The 100 kyr peak in the data in (a) and (b) do not fit the fingerprints from the theories (c) and (d), but are a good match to the prediction from inclination in (e). return to beginning


Far more important to our present analysis, however, is the fact that the predicted 100 kyr "eccentricity line" is actually split into 95 and 125 kyr components, in serious conflict with the single narrow line seen in the climate data. The splitting of this peak into a doublet is well known theoretically (see, e.g., ref 5), but in comparisons with data the two peaks in the eccentricity were merged into a single broad peak by the poor resolution of the Blackman-Tukey algorithm (as was done, for example, in ref 8). The single narrow peak in the climate data was likewise broadened, and it appeared to match the broad eccentricity feature.

***

Figure 3. Variations of the inclination vector of the Earth's orbit. The inclination i is the angle between this vector and the vector of the reference frame; Omega is the azimuthal angle = the angle of the ascending node (in astronomical jargon).. In (A), (B), and (C) the measurements are made with respect to the zodiacal (or ecliptic) frame, i.e. the frame of the current orbit of the Earth. In (D), (E), and (F) the motion has been trasformed to the invariable frame, i.e. the frame of the total angular momentum of the solar system. Note that the primary period of oscillation in the zodiacal frame (A) is 70 kyr, but in the invariable plane (D) it is 100 kyr.

 

 

 

 

Ice Ages & Astronomical Causes
Brief Introduction to the History of Climate
by Richard A. Muller

Origin of the 100 kyr Glacial Cycle

Figure 1-1 Global warming

Figure 1-2 Climate of the last 2400 years

 

Figure 1-3 Climate of the last 12,000 years

Figure 1-4 Climate of the last 100,000 years

Figure 1-5 Climate for the last 420 kyr, from Vostok ice