INFOBOX 2.1 Orbital forcing of glacial - interglacial cycles

One of the natural climate forcings is the so-called orbital forcing, besides others, such as the variation in solar irradiance and volcanic eruptions.The orbital forcing depends on changes in the Earth's orbit around the Sun and is the result of variations of the following parameters: the orbit's eccentricity, the obliquity of the Earth's orbit with respect to the ecliptic plane, and the axial and apsidial precession, i.e., the precession of the Earth's rotation axis and the precession of the Earth's orbital ellipse around the Sun.The latter two are often combined into one process.Orbital forcing yields significantly different irradiance values for the two terrestrial hemispheres at high latitudes but has almost no effect on the mean total energy.The dominant forcing determining the ice ages is the one on the northern hemisphere.