It is possible to roughly map out the history of the peopling of the earth as a process looping back over itself on different scales: after a long initial nomadic phase, during which densities were very low (which does not preclude the migrations over long distances that populated the earth), in the wake of the arrival of agriculture human habitats developed that were a hundred times more dense, entertaining a very close relationship with their local environments (Diamond, 1999).
Cities emerged within agrarian societies, but in this period they only amounted to around 10% of the total population (Bairoch, 1985). When, towards the end of the 18th century in Europe, a second transition turned rural habitats into urban habitats as a result of productivity gains arising from industrial and organisational innovation, the centres of urban population developed network dynamics, much less subject to conditions prevailing in their individual environments. Over the last two centuries cities have become integrated into city systems in which they have also become increasingly interdependent (Pumain, 2006).
This dynamics of emulation among cities has strengthened even further their propensity for growth and innovation. In the course of the 21st century, this will attract around three quarters of the world population to cities, as is already the case in the wealthy nations. Nevertheless, this dynamic is already encountering ecological limitations (energy resources, raw materials, land availability, pollution) which are re-establishing strong interactions between populations and the natural environment, this time on a global scale, and in an uneven manner from one city to another since their resilience is variable. The exhaustion of certain non-renewable resources is sharpening competition, and the perspective of the measures that are required to counter the effects of global warming are generating concern.
To summarize this urban evolution and parameterize the changes in dynamic regimes,some new Simpop models are currently designed:
Another important part of the project in 2011-2012 is the design and developpement of SimProcess, a methodology and a platform based on massive grid computing, dedicated to experiment with spatial simulation models and which would offer some multi-scale evaluation methods.To that end, we're working with the OpenMole team of the Paris complex systems institute.
Two new models are designed within this new framework : MARIUS and the China-India Model