Electronic Thesis and Dissertation Repository


Master of Science


Applied Mathematics


Xingfu Zou


The aim of this thesis is to model the impact of climate change on polar bear populations. The first model is a discrete matrix model with time-dependent parameters, which are influenced by temperature increases. Sensitivity analysis is done on the model. Numerical simulations predict there exist several scenarios that result in polar bear extinction. When the impact of climate warming is low the population is predicted to die out in 300 years and for higher levels of impact the population can be extinct within 6. The second model is a system of continuous delay differential equations with time-dependent parameters, also influenced by increasing temperatures. The positivity of solutions is found, dependent on sufficient initial conditions. Numerical simulations predicted a threshold value for the impact of temperature. The population always goes extinct if impact is beyond this threshold. The smallest impact predicts extinction in 150+ years and largest in 5 years.