Dresden 2011 – wissenschaftliches Programm
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UP: Fachverband Umweltphysik
UP 4: Climate; jointly with Arbeitsgruppe Junge DPG (AGjDPG)
UP 4.4: Vortrag
Mittwoch, 16. März 2011, 15:45–16:00, HSZ 201
Initiation of a Marinoan Snowball Earth in a state-of-the-art atmosphere-ocean general circulation model — •Aiko Voigt1,2, Dorian S. Abbot3, Raymond T. Pierrehumbert3, and Jochem Marotzke1 — 1Max Planck Institute for Meteorology, Hamburg, Germany — 2International Max Planck Research School on Earth System Modelling, Hamburg, Germany — 3Department of Geophysical Sciences, University of Chicago, Chicago, Illinois, USA
The apparent existence of low-latitude land glaciers at sea level during the Marinoan (∼635 Ma) has led to the proposal that these glaciations were accompanied by completely ice-covered oceans. These states have become popular under the term “Snowball Earth.” In this contribution, we study the initiation of a Marinoan Snowball Earth with the most sophisticated model ever used for this purpose, the atmosphere-ocean general circulation model ECHAM5/MPI-OM. In particular, we focus on the total solar irradiance and atmospheric concentration of carbon dioxide needed to trigger a Marinoan Snowball Earth. We find that Snowball initiation in this model is much easier than found in various previous modelling studies. A zero-dimensional energy balance model is used to predict the Snowball Earth bifurcation point from only the equilibrium global mean ocean potential temperature for present-day TSI. We do not find stable states with sea-ice cover above 55%, and land conditions are such that glaciers could not grow with sea-ice cover of 55%. Therefore, none of our simulations qualifies as a “slushball” solution, with the caveat that mountains are not included in our study.