What caused Earth's orbital change 125,000 years ago?

[jnorman]

last night i was watching a public broadcasting special about climate change, and they mentioned that 125,000 years ago there was a large peak in CO2 in the atmosphere which caused a rise in global temp. they stated that the effect was caused by a "change in the Earth's orbit around the sun."

what happened 125,000 years ago that would have caused a change in the Earth's orbit significant enough to affect the global climate? thanks.

 

[D H]

http://en.wikipedia.org/wiki/Milankovitch_cycles

 

[jnorman]

thanks DH - that helped.