Uncertainty analysis and detection of structural changes in environmental systems dynamics for a better understanding of climatic and anthropogenic risks

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Progress in numerical technologies, as well as greater processing speed, has prompted the use of complex environmental models for research, design and planning purposes. Nowadays, powerful computer codes are available to describe nearly any environmental process of interest. As evidence for catastrophic impact of global warming grows at an alarming rate, the current practice is to use these models for impacts estimation after calibration using observed data. However, the issue of consistency is rarely considered: will a model that is performing relatively well in the current climate provide trustworthy results in a changed climate? In hydrology, nearly all categories of models have been used, unfortunately with very little attention if any to the suitability of the chosen environmental model under future climatic conditions. Black-box models should be used with extreme caution for such studies, since it is well known that the parameters of black-box models capture a lot of information related to the calibration conditions. In this case, the implicit assumption of consistency in a watershed's response to climate does not hold. The latter statement applies, in principle at a lesser extent, to physics-driven and conceptual models, which always involve some parameterisation and calibration. Since global warming is driving earth's climate in an unprecedented manner, insight is needed as to how a particular model can be expected to perform in the future climate.