2005 Climate change and the hydrological cycle

ABSTRACT: The threat of climate change has increased interest in climate research, which focuses on observing, understanding and modelling the five interconnected components that comprise the climate system: atmosphere, oceans, land surface, cryosphere, and biosphere. Feedbacks at a variety of spatial and temporal scales shape the system’s overall behaviour, and the hydrological cycle plays a critical role in this respect, via two important feedback processes that involve water vapour and clouds. Climate modelling improves understanding of climate processes and characteristics, and several approaches are available, from simple models to general circulation models (GCM). GCMs offer the most realistic simulations of the global and continental climate, but cannot provide the most important climatic variables to regional-scale hydrological modelling. Therefore, many research groups have begun to use regional circulation models to downscale the coarse-resolution information generated by GCMs; they then apply these driving-fields to hydrological models. Downscaling improves the representation of climatic behaviour, but does not allow for feedback between models. Simple models may offer an alternative for certain hydrological applications. 1