The Eocene-Oligocene Transition as a Cascading Tipping Event

Abstract

The global climate transition which occurred approximately 33.7 Ma ago at the Eocene-Oligocene transition is characterised by a still largely unexplained two step cooling of the Earth, separated by a 200 kyr plateau visible in proxy data. Study by Tigchelaar et al. (2011) suggests the potential explanation where a transition in the ocean overturning circulation induces the inception of Antarctic land ice, effectively cooling the Earth in a step-wise manner. In this thesis, we will discuss the behaviour of cascading fold bifurcating dynamical systems, as introduced by Dekker et al. (2018), and apply these concepts to the ocean and land ice systems, to argue that the Earth’s climate can be interpreted as such a cascading system. Through numerical simulation using the box model devised by Gildor and Tziperman (2000, 2001), Gildor et al. (2002), and subsequently adapted by Tigchelaar et al. (2011), we present qualitative manifestations of this cascading behaviour, and argue that stochastic noise or insolation variability has the potential to induce the plateau observed in proxy data.