In the 1920's Milutin Milankovitch proposed that the ice ages on Earth are caused by changes in solar insolation (the amount of sunlight) due to changes in the Earth's orbit (which are caused by gravitational interactions between the Earth and Jupiter and the other planets). Fourier analysis of 600 kyrs of global climate data shows a strong peak at 100 kyr (Figures A and B) that the Milankovitch theory attributes to changes in the Earth's eccentricity (Figures C and D). Comparison of the data (figures A and B) with the theory (figures C and D) show that the Milankovitch hypothesis does not properly account for the data. We proposed that changes previously ignored orbital parameter, the inclination of the Earth's orbit, account for the 100 kyr cycle. The spectrum of these changes, shown in Figure E, is a good match to the data.
A detailed paper containing this spectral analysis has been submitted to NATURE.