Causes of Climate Change 
2.5.2.1. Obliquity
Today the Earth is tilted on its rotational axis at an angle of 23.4° relative to a perpendicular to the orbital plane of the Earth. Over a 41,000 year time period, this angle of inclination fluctuates between 22° and 24.5°, influencing the latitudinal distribution of solar radiation.
Obliquity does not influence the total amount of solar radiation received by the Earth, but affects the distribution of insolation in space and time. As obliquity increases, so does the amount of solar radiation received at high latitudes in summer, whilst insolation decreases in winter. Changes in obliquity have little effect at low latitudes, since the strength of the effect decrease towards the equator. Consequently, variations in the Earth's axial tilt affect the strength of the latitudinal temperature gradient. Increased tilt has the effect of raising the annual receipt of solar energy at high latitudes, with a consequent reduction in the latitudinal temperature gradient.
External Forcing
-Galactic Variations
-Orbital Variations
·Obliquity
·Eccentricity
·Precession
·Milankovitch
-Solar Variations
Internal Forcing
-Orogeny
-Epeirogeny
-Volcanic Activity
-Ocean Circulation
-Atmosphere