From Molecules to Ecosphere

Chairs & Co-Chairs

Daniel Schertzer


The physical, chemical and biological environment of humans – from the local, community level to the global, planetary one – represents a rapidly increasing concern of the post-industrial era. Its study involves all the subsystems of the Earth system – the atmosphere, oceans, hydro- and cryosphere, as well as the solid Earth?s upper crust – along with their interactions with the biosphere and with human activities. We are therefore dealing with a highly complex, heterogeneous and multiscale system, and with an exceedingly interdisciplinary set of approaches to it. The concepts and tools of complex-system theory seem particularly useful in attacking three major challenges. Firstly, the range of uncertainties still prevailing in future climate change projections has until now been attributed largely to difficulties in parameterizing subgrid-scale processes in general circulation models (GCMs) and in tuning semi-empirical parameters. Recent studies also point to fundamental difficulties associated with the structural instability of climate models and suggest applying the theory of random dynamical systems to help reduce the uncertainties. Secondly, the Earth system varies at all space and time scales and is thus out of and probably far from thermodynamic equilibrium. The methods of statistical physics are therefore of interest in modeling the system?s near-equilibrium behavior and then extending the results farther away from equilibrium. Finally, much of the interest in this area arises from concern about the socio-economic impact of extreme events. The study of their statistics and dynamics can lead to a deeper understanding and more reliable prediction of these events.