The Mid Pleistocene Transition from Budyko's Energy Balance Model

Energy Balance Models (EBMs) are arguably the simplest form of global climate models. However, the simplicity of such models allows for a deeper mathematical analysis that complements the understanding gained from more complex models. Here we revisit the long-standing question of what dynamical processes are responsible for the Mid Pleistocene Transition and argue that a novel low-order "flip flop" model on the basis of the EBM formulated by Mihail Budyko in 1969 might give us some new insights. This EBM was recently extended with two equations of latitudinal averaged quantities, one for the snow or albedo line, and one for the maximum ice extent. This system of three ordinary differential equations admits glacial cycles with similar characteristics to the proxy records. Furthermore, we demonstrate that a critical bifurcation parameter is linked to the LR04 stack of benthic d¹⁸O records and that this simple model remarkably shows a realistic Mid Pleistocene Transition. We discuss the physical mechanisms that might determine the critical bifurcation parameter and how they relate to the Mid Pleistocene Transition.