Special issue  

Building upon Milancovic’s theory of orbital forcing, this manuscript reviews the interplay between intrinsic variability and external forcing in the emergence of glacial-interglacial cycles. It provides the reader with historical background information and with basic theoretical concepts used in recent paleoclimate research. Moreover, it presents new results which confirm the reduced stability of glacial-cycle dynamics after the Mid-Pleistocene Transition.

Over the last 2.6 Myr, the Quaternary period has been marked by the alternance of extended and reduced Northern Hemisphere ice sheets, known as the glacial-interglacial cycles. With a simple model, we are able to reproduce the main features of the ice volume evolution, like the switch of periodicity – from 41 kyr cycles to 100 kyr cycles – that is observed in the data after 1 Ma BP. The quality of the model-data agreement depending on the input insolation and period considered are discussed.