WCAMA: Palestra 2: "‘Tipping points’ for the Amazon Forest"
Carlos Nobre (CPTEC/INPE)
09:40 - 10:30
Local: Auditório 2

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.