L'humanité face à l'effet de serre additionnel qu'elle crée

The likely anthropogenic climate change impacts are summarized, as well as the adaptation capabilities and the possibilities of controlling the greenhouse gas concentration in the atmosphere. A number of physical and biological systems have already been impacted by the observed temperature increases. The main domains at risk are discussed: hydrology and water resources, agriculture and food security, terrestrial ecosystems, oceans and coastal zones. Problems specific to Europe are presented. The share of the various activity sectors in the emission of greenhouse gases and the possibilities of reducing these emissions are discussed. Costs and benefits of mitigation actions can be estimated under a number of assumptions that are recalled. The results of the major economic studies are presented. The long-term efficiency of the mitigation actions is linked with their generalization to all countries in the world.