Milankovich cycle
A study of the Antarctic ice core, using oxygen-nitrogen ratios in air bubbles trapped in the ice, concluded that the climatic response documented in the ice cores was driven by Northern hemisphere insolation as proposed by the Milankovitch hypothesis. This is an additional validation of the Milankovitch hypothesis by a relatively new method. It is not consistent with the "inclination" theory of the 100,000-year cycle.