Farside99 (and similar) the ice ages are predicted by the Milankovitch cycles, three cycles cosmologists recognize as causing regular changes in Earth’s climate by changes in shape of the Earth’s orbit around the sun, the Earth’s axial tilt and precession of tilt. These cycles are approximately 21,000, 43,000 and 100,000 years long and proven by archeological evidence and ice cores from glaciers still existing. They show that we should be slowly approaching an ice age and cooling off. The fact that the Earth is slowly warming up (“global” means an average of temperatures from all around the world, not just from a couple of selected spots) points out the disruption of natural cycles. You might want to investigate the thermo-haline conveyor system and how melting glaciers affect it.