This chapter contains sections titled: Introduction Onset of Northern Hemisphere Glaciation. Glacial-Interglacial Cycles The Mid-Pleistocene Revolution Rapid Climate Changes in Glacial Periods Rapid Climatic Changes During the Last Glacial-Interglacial Transition Rapid Climate Changes within Interglacials The Future Appendix I: Orbital Forcing; the Basics [Adapted from Wilson Et Al, 2000 and Lowe and Walker, 2000]