Thought you might to read this link - http://en.m.wikipedia.org/wiki/Milankovitch_cycles
Milankovitch cycles and a variety of other phenomena such as the Earth’s other orbital mechanics, rotational precession, magnetic pole reversals, lengthening diurnal rotation (longer days), reducing lunar tidal forcings, and so forth represent much smaller and shorter influences when compared to the vastly larger changes in atmospheric mass and composition by inorganic and organic influences. There are for some examples the expression of the Milankovitch cycles in the varves of the Devonian, when the development of the first forests upon the Earth radically increased the concentration of oxygen in the atmosphere while more than halving the already trace amounts of carbon dioxide, which resulted in another major ice age and a mass extinction event. When you are doing geological field work, you can see in the varves how the water levels changed in synchronization with the Milankovitch cycles, but the far larger events ended these sequences with overwhelming changes to the geomorphology, sea levels, and related biosphere. It is always provocative to see the media go on about the Milankovitch cycles in connection to the stages of the curreent ice age while totally neglecting the many other vastly more forceful changes in the Earth’s inherent composition and solar luminosity.