The Mid-Pleistocene Transition: a dynamical systems approach

Abstract

In this project, we investigated the Mid-Pleistocene transition (the change of glacial period from 41 kyr to 100 kyr, around 800 kyr ago), with a dynamical systems approach. By first introducing the mathematical structure for such transitions in systems (dynamical systems, bifurcations and tipping), this can use this theory to find 100 kyr cycles in dynamical systems and simulate transitions such as the MidPleistocene transition (MPT). This is first investigated in the conceptual climate model of Saltzman and Maasch. By first studying a simplified version of this model, a thorough bifurcation analysis is performed. By knowing more about the dynamics of the model, it is possible to simulate the MPT in this model by crossing a Hopf bifurcation. Although this does not give a proof of a physical mechanism that triggers the MPT, it seems that MPT-like transitions are (in these systems) triggered by parameter(s) in the CO2 equations. Later on, also MPT-like transitions are simulated in the more physics-based model of Gildor and Tziperman. In this model, only a small change in parameters (seemingly without crossing a bifurcation) is enough to simulate MPT behavior.