Modelling climate change impact on phosphorus load in Swedish rivers

Climate change impact on phosphorus load is modelled and compared for two Swedish rivers with different characteristics. The modelling was based on the ECHAM4/OPYC3 B2 scenario, downscaled with the RCA3 model and a complementary scaling procedure. Hydrology and phosphorus concentrations were simulated for the time period 1961–2100, using the ICECREAM model for arable leaching, and HBV-NP model for integrated catchment analysis including all sources, erosion and major turnover processes at the catchment scale. The results show 10% increased load, and 25% reduced load, respectively, for the rivers. In both catchments, phosphorus leaching from crops was found to increase; however, this load was only a minor fraction in one river. For the other river, a suggested plan of measures for reducing load was found to be less effective in a future climate. Finally, the study concludes that climate change impact studies are based on a chain of assumptions and uncertainties which should be emphasised in future research.