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Abstract:
At the IGBP (International Geosphere-Biosphere Programme) workshop held in Potsdam, Germany, on June 15-16, 1999, the state of the art of modelling the natural Earth system was reviewed. It became apparent that Earth system modelling has to rely on a hierarchy of models in which models of intermediate complexity can play a central role. Depending on the nature of questions asked and the pertinent time scales, there are, on the one extreme, conceptual, more inductive models, and, on the other extreme, three-dimensional comprehensive models operating at the highest spatial and temporal resolution currently feasible. Models of intermediate complexity bridge the gap. The so-called EMICs describe most of the processes implicit in the comprehensive models, albeit in a more reduced, i.e., more parameterized form. They nevertheless simulate the interactions among several, or even all components of the Earth system explicitly. Moreover, EMICs are simple enough to allow for long-term simulations over several 10,000 years or a broad range of sensitivity experiments.
Up to now, there is no concise definition of an EMICs. Perhaps, this will presumably never be achieved, because the border between EMICs and comprehensive models will change with time and computer capacity. Therefore, in a follow-up workshop in Nice, in April 2000, it was decided to publish a table of EMICs which are currently in operation. The first Table of EMICs was discussed in a multi-authored paper by [Claussen et al., 2002, Climate Dynamics, 18]. Several EMIC intercomparison workshops followed which include studies of sensitivity to changes in atmospheric CO2 concentrations [Petoukhov et al., 2005, Climate Dynamics, in press], to historical land cover change [Brovkin et al., 2005, Climate Dynamics, submitted), and an assessment of the stability of the Atlantic meridional overturning circulation [Rahmstorf et al., 2005, submitted].
