Biogeosciences www.biogeosciences.net 1726-4170 1726-4189 4 5 2007 10.5194/bg-4-707-2007 http://www.biogeosciences.net/4/707/2007/ http://www.biogeosciences.net/4/707/2007/bg-4-707-2007.html http://www.biogeosciences.net/4/707/2007/bg-4-707-2007.pdf 707 714 2007-08-28 Multiple steady-states in the terrestrial atmosphere-biosphere system: a result of a discrete vegetation classification? A. Kleidon akleidon@bgc-jena.mpg.de K. Fraedrich C. Low Biospheric Theory and Modelling Group, Max-Planck-Institut für Biogeochemie, Postfach 10 01 24, 07701 Jena, Germany Meteorologisches Institut, Universität Hamburg, Bundesstr. 55, 20146 Hamburg, Germany Department of Geography, University of Maryland, 2181 Lefrak Hall, College Park, MD 20742, USA Multiple steady states in the atmosphere-biosphere system can arise as a consequence of interactions and positive feedbacks. While atmospheric conditions affect vegetation productivity in terms of available light, water, and heat, different levels of vegetation productivity can result in differing energy- and water partitioning at the land surface, thereby leading to different atmospheric conditions. Here we investigate the emergence of multiple steady states in the terrestrial atmosphere-biosphere system and focus on the role of how vegetation is represented in the model: (i) in terms of a few, discrete vegetation classes, or (ii) a continuous representation. We then conduct sensitivity simulations with respect to initial conditions and to the number of discrete vegetation classes in order to investigate the emergence of multiple steady states. We find that multiple steady states occur in our model only if vegetation is represented by a few vegetation classes. 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