If we can agree that the earth changes orbit and tilt and that in turn causes heating and cooling cycles of the earth as well as solar radiation then we have a place to start from.

Heating of the earth's core as a result of  these changes increases the amount of precipitation which increases the amount of snow and reflected light which in turn creates cooling temperatures and brings on an ice age.

Greenhouse gases also increase the water vapor, increasing the snow, triggering an ice age.  Like I said before, its cyclical, maybe we sped up the cycle a few decades.  In the galactic scale its a non-event.

Either way we better start building bio-spheres with fusion energy reactors.

Don't waste your vote, vote Green or Independent in the next election.