Actually its not warming, its cooling. And it is natural, humans don't have anything with it (no mater how that can hurt the ego).
That knows everyone who reads books and don't just watch CNN (not to mention loads of free books on the internet). Unfortunately not all the people have hardware to process it.
This winter we will fly BoB-SoW in very, very cold rooms.
http://www.homepage.montana.edu/~geo...1/milankov.htm
http://en.wikipedia.org/wiki/Milankovitch_cycles
http://www.eoearth.org/article/Milankovitch,_Milutin