HR: 17:50h
AN: NG54A-07    [Abstracts]
TI: Multiple Steady States Versus Optimality in the Atmosphere-Biosphere System
AU: * Kleidon, A
EM: akleidon@bgc-jena.mpg.de
AF: Axel Kleidon, Max-Planck-Institut fuer Biogeochemie Hans-Knoell-Str. 10, Jena, 07745, Germany
AU: Richter, S
EM: srichter@bgc-jena.mpg.de
AF: Axel Kleidon, Max-Planck-Institut fuer Biogeochemie Hans-Knoell-Str. 10, Jena, 07745, Germany
AB: Multiple steady states (MSS) can emerge from complex system dynamics as a result of interactions and positive feedbacks. As a result of MSS, the emergent state of the system depends on the initial conditions. An example for MSS is the interaction of vegetation with precipitation, where more vegetation cover enhances atmospheric moisture recycling, thereby enhancing vegetation cover in water-limited regions. One alternative view is that vegetation is optimally adapted to its environment, thereby maximizing its dissipative activity (which is consistent with the principle of Maximum Entropy Production, MEP). We used a coupled vegetation-climate model of intermediate complexity and conducted simulations that compare these two approaches. To demonstrate the concept of MSS, we conducted simulations with prescribed biomass and precipitation levels and found that the model in most cases only yields one steady state. We then performed additional sensitivity simulations to vegetation form and function to demonstrate that there is a range of possible steady states that differ in their associated vegetation productivity. From these results we conclude that it is more appropriate to view the atmosphere-biosphere system as a complex dissipative system with many degrees of freedom with many possible steady states in which optimization can take place rather than a system that operates merely within a few steady state solutions.
DE: 1620 Climate dynamics (0429, 3309)
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
DE: 4410 Bifurcations and attractors
DE: 4430 Complex systems
DE: 4435 Emergent phenomena
SC: Nonlinear Geophysics [NG]
MN: 2007 Joint Assembly