Global hydrological changes associated with a perturbation of the climate system : the role of atmospheric feedbacks, their uncertainty and their validation

The anthropogenic increase of the atmospheric greenhouse effect is expected to bring important perturbations of the climate system during the next century. The models which are used to compute scenarios of this future climate change nevertheless suffer from important uncertainties which make impossible the detailed prediction of regional impacts. Characterizing these uncertainties as precisely as possible constitutes a necessary step to assess a climate risk and realize local impact studies. We describe the manifestation of water vapour and cloud feedbacks in the present models, and show that satellite data, in particular, may constitute an important source of information to constrain more efficiently the models.