Changes in the earths orbit through time causes changes in the amount of sunlight that reaches earth. There are also three different things that are thought to have an important role in causing ice sheets. These things are changes in the eccentricity of the earths orbit, changes in the tilt of the earthÕs axis, and the procession of the equinoxes. Changes in the tilt of the earths orbit cause changes in the distribution of radiation at high latitude and the length of dark periods at the poles. Differences in radiation of this level, is one of the biggest factors that influences the making and melting of these ice sheets. Today the tilt is approximately twenty-three point five degrees. The tilt varies from between twenty-one point six and twenty-four point five.

The effects of precession on the amount of solar radiation that gets to the earth is just like the effects of tilt. Differences in these two cause radiation changes of up to fifteen percent at high latitudes. The changing aphelion and perihelion is also important for the climate because it affects the seasons and the amount of radiation. They change position on the orbit through a cycle of three hundred and sixty days.

The Earths orbit around the sun is an ellipse not a circle, which is measured by eccentricity, that fluctuates from between one and five percent through time. This affects the amount of radiation the earths surface receives at aphelion and perihelion. Even thought the amount of change in radiation is very small it is apparently important in the making and melting of the ice sheets.