
January 28, 2014 

A report on 'Glacial/interglacial variations in atmospheric carbon dioxide,' by Sigman and Boyle,
Kate Meyer, School of Mathematics 


Feedback between temperature and global carbon storage not only illuminates Earth's history but also informs climate change predictions. In their 2000 paper, Sigman and Boyle seek to account for the roughly 100 ppmv observed decrease in atmospheric carbon dioxide during glacial periods. We will review their arguments that (1) the land provided a source, not sink, of carbon; and (2) changes in the oceanic biological pump are most likely responsible for glacialage carbon sequestration. 


February 4, 2014 

Interpreting the Past: Modeling the 100,000 year Problem,
Samantha Oestreicher, School of Mathematics 


February 18, 2014 

Decoding the Past: Rejecting a Dynamic Hopf Model,
Samantha Oestreicher, School of Mathematics 


March 4, 2014 

Ducks in the Ocean: Canards and Relaxation Oscillations in Largescale Ocean Dynamics,
Andrew Roberts, University of North Carolina 


Stommel's 1961 thermohaline circulation model provides evidence that the ocean exhibits bistability. Understanding how the ocean may switch between these stable circulation states has implications for paleoclimatic events such as DansgaardOeschger events. A modified version of Stommel's model is analyzed, approaching the problem from a fast/slow dynamics perspective. Because the model is only piecewisesmooth, the standard fast/slow theory is not sufficient. In addition to the analysis of the model, this talk will also discuss the new mathematical developments required to attack the problem: namely canard cycles in piecewisesmooth systems and a nonsmooth bifurcation called a 'superexplosion.' 


March 11, 2014 

Nonsmooth Phenomena in Conceptual Climate Models,
Anna Barry, Institute for Mathematics and its Applications 


March 25, 2014


Huybers' Model of Glacial Cycles,
Jonathan Hahn, School of Mathematics 


Huybers determined that past deglaciations are triggered at a particular phase of the Earth's obliquity and came up with a simple model that reflects this using a threshold to determine deglaciation timing. Increasing the threshold in the model can reflect the shift we see from 40,000 to 100,000 year glacial cycles. We will look at this model and some of its mathematical implications. 


April 1, 2014 

Phaselocking in a model for glacial variability,
David Morawski, School of Mathematics 


