Richard McGehee
The Mathematics of Climate Seminar
University of Minnesota
School of Mathematics


Spring 2014 Schedule


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 glacial-age carbon sequestration.
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February 4, 2014
       Interpreting the Past: Modeling the 100,000 year Problem, Samantha Oestreicher, School of Mathematics
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February 18, 2014
       Decoding the Past: Rejecting a Dynamic Hopf Model, Samantha Oestreicher, School of Mathematics
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March 4, 2014
       Ducks in the Ocean: Canards and Relaxation Oscillations in Large-scale 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 Dansgaard-Oeschger events. A modified version of Stommel's model is analyzed, approaching the problem from a fast/slow dynamics perspective. Because the model is only piecewise-smooth, 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 piecewise-smooth systems and a non-smooth bifurcation called a 'super-explosion.'
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March 11, 2014
       Nonsmooth Phenomena in Conceptual Climate Models, Anna Barry, Institute for Mathematics and its Applications
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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.
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April 1, 2014

       Phaselocking in a model for glacial variability, David Morawski, School of Mathematics
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Last update: April 6, 2014 ©2014 Richard McGehee