Master Thesis Defense by Jade Omotoyosi Nina Brauns

Title: Investigating the dynamics of cusp bifurcations: A conceptual model for glacial-interglacial cycles

Abstract:
An investigation into the dynamics of a two-parameter family of non-linear differential equations inspired by MacAyeal (1979) reveals the utility of simple conceptual models in understanding the non-linear climate response to linear forcing. A simple model is used to explain the non-linear response to insolation forcing after the Mid-Pleistocene Transition (MPT) which produces behaviour similar to the saw-toothed glacial cycles in the paleoclimate record. Global ice volume is taken to be a function of two independently varying parameters, the solar insolation and ‘alpha’, a secondary control parameter. The control parameter 'alpha' is suggested to be related to internal dynamics of the climate system, possibly ice sheet dynamics. The transition in period of glacial cycles at the MPT is suggested to occur as a result of northern hemisphere glaciers exceeding a critical threshold, which changes the timescales of the growth and decay of ice sheets, causing the asymmetric, lower frequency,  higher amplitude glacial cycles in the Late Pleistocene.

Supervisor: Peter Ditlevsen
Censor: Jens Olaf Pepke Petersen, DTU