  Using a recent conceptual model of the glacial-interglacial cycles we present
more evidence of Milankovitch cycles being the trigger for retreat and forming
of ice sheets in the cycles. This model is based on a finite approximation of
an infinite dimensional model which has three components: Budyko's energy
balance model describing the annual mean temperatures at latitudes, Widiasih's
ODE which describes the behavior of the edge of the ice sheet, and Walsh et al.
who introduced a snow line to account for glacial accumulation and ablation
zones. Certain variables in the model are made to depend on the Milankovitch
cycles, in particular, the obliquity of the Earth's axis and the eccentricity
of the Earth's orbit. We see as a result that deglaciation and glaciation do
occur mostly due to obliquity and to some extent eccentricity.
