Scientific publications

Climate change impact simulations for hydrological processes in the Nordic region for the period 2071-2100 have been estimated using results from global climate models from the Hadley Centre and the Max-Planck Institute, and dynamical downscaling using the Rossby Centre RCAO and RegClim HIRHAM regional climate models. These climate scenarios were used for driving the HBV and WaSim-ETH hydrological models. Present conditions were determined from control runs using observed meteorological data and climate model results for 1961-1990. Maps presenting the spatial distribution of hydrological state variables and fluxes are presented. A moderate increase in annual runoff is expected in most parts of the Nordic region, with a decline in some parts for some scenarios. The changes depend on the spatial distribution of the atmospheric pressure fields as modelled by the two global climate models. Significant changes in the seasonal distribution of runoff are expected. Increase everywhere in the winter, increase in mountainous basins and inland basins in the spring and a decline in coastal and southern basins in the spring. Decrease will occur everywhere in the summer, while autumn runoff will increase everywhere except in southern parts. The occurrence of large snowmelt floods is likely to become more seldom due to earlier snowmelt and reduced snow storage. The combined effect of increase in rainfall intensities, number of rainfall events and total rainfall volume will most likely provide conditions that may be expected to yield larger rain floods.