In this thesis, I address these questions by combining field data collected from a paleo-climatic perturbation in the South Pyrenean foreland basin with 2 sets of physical experiments. In particular, I first investigate how grain size distribution and channel geometry evolved during a well-documented global extreme warming event (Palaeocene-Eocene Thermal Maximum, PETM) in a well-exposed section in the South Pyrenees (Esplugafreda section), with these data I propose a reconstruction of paleo-channel slope and hydraulic conditions during that extreme event. Third, I perform a series of physical experiments, which focused on possible autogenic signals in the architecture of the deposits studied in the South Pyrenees. Fourth, following the questions addressed above, I try to test experimentally studying the river response observed in the natural example, with focus on perturbations of upstream boundary conditions. In the following paragraphs, I briefly summarize my results for each of these topics.