There is also another theory about which way the Earth tilts, this is more region specific heating. Every 41,000 years the Earths axis will flip over to the other side. Magnetic South will be at the top of the compass and Magnetic North at the bottom. (Don't worry, your precious GPS Navigation will still work correctly...)
As the Earth tilts, different areas of the Earth are exposed more to the sun than the rest, so we have regional climate change.
As the poles change, the position of the magnetosphere is changed relative to the sun. The magnetosphere is what guards the earth from most of the radiation that attempts to burn your skin and bleach the papers and posters you may hang in windows.
That is were we get changes like in the Mid-East, Thousands of years ago in Mesopotamia, near the Tiber and Euphrates Rivers was all tropical and had lush forests, but is now a desert.
This could be the cause of the Polar ice caps melting. "Why would this affect the Global Temperature?" you say! Well, when the polar ice caps melt and the dark, heat-absorbing ocean is exposed, more heat is absorbed faster than is absorbed by mountains, snow-caps and deserts.