A minimal conceptual model for glacial–interglacial cycles

The Pleistocene glacial cycles are believed to be a climatic response to astronomical variations in the incoming solar radiation or insolation. This response is far from linear; thus, intricate internal dynamics of the climate system are at play. MacAyeal (MacAyeal 1979 J. Glaciol. 24, 245-257. (doi:10.3189/S0022143000014775)) proposed a simple nonlinear differential equation as a conceptual model of glacial cycles with a parameter-dependent change of response experienced at the Mid-Pleistocene Transition (MPT) from a 41 kyr cyclic response to the present approximately 100 kyr cyclic response to astronomical forcing. However, MacAyeal did not compute numerical solutions of the model. This is presented here, where we test the hypothesis that a structural change, governed by a 'slow' control parameter, 'α', explains the MPT and time-asymmetric (sawtooth-shaped) post-MPT glacial cycles. This article is part of the theme issue 'Critical transitions and intelligent control in complex systems'.