Slide 30 in this series.
The variations in both the earth's orbit as well as the sun's affects the earth's climate.
There quite a few cycles in this system. There is also a galaxy variation in cosmic rays that has a cycle of few million years. This is as a system quite complex.
NEXT: The orbial complexity of the earh and sun can be diagrammed.
These links are the topics for this section.
Modelling Temp Natural Factors
Earth and the Science of Radiation
Milankovith Overlapping Cycles