Palestras

Management of socio-ecological systems: the multi-agent approach

Palestrante: Jean-Pierre Müller (CIRAD/France – UPR no.47/GREEN)

Socio-ecological systems are complex systems where the interactions between the biophysical dynamics and the social dynamics produce global behaviors that are difficult to understand and to manage. First we shall introduce the notions of complex systems and emergence, showing why these concepts are applicable to socio-ecological systems. Then we shall introduce the various possible approaches to complex system modeling and the particular place of the multi-agent systems in these approaches. The multi-agent approach shall be illustrated thorough an example for companion modeling where various implementations of multi-agent systems are used in interaction with the concerned stakeholders.

‘Tipping points’ for the Amazon Forest

Palestrante: Carlos A Nobre (Centro de Ciência do Sistema Terrestre –
CST/Instituto Nacional de Pesquisas Espaciais – INPE)

The stability of the Amazon forest-climate equilibrium is being perturbed by a number of human drivers of change (e.g., deforestation, global warming, forest fires, higher CO2 concentrations and increased frequency of droughts and floods). Quantitative assessments for the maintenance of the tropical forest carried out using complex mathematical models of the global and regional climate-vegetation system indicate that “tipping points” may exist for total deforested area (> 40%) and for global warming (Delta T > 3 to 4 C). The interpretation of tipping points for the climate-vegetation system is that, if they are transgressed, the system would sometimes abruptly reach a new equilibrium state and the simple removal of the disturbance that originally caused the state to tip will not make it to bounce back to the original equilibrium state and the time scale for full recovery could be very long. The likelihood of exceeding a tipping point can be greatly exacerbated by increases in forest fires and droughts, but quantification of those effects is still lacking. Forest resilience can be significantly increased if CO2 ‘fertilization’ effect is proven to be taking place for tropical forests, but it can be offset by continued increases in temperature, rainfall seasonality and forest fires. Assessing the likelihood of tipping points for forest maintenance can be useful for risk assessments and as a guide to conservation policies for the Amazon.

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