Description: The aim of the study is to analyse possible future changes in the Baltic Sea wave conditions and to project coastal changes in six differently exposed Estonian coastal sections resulting from changing wind climates. In the open parts of the Baltic Sea, the SWAN model with 3 NM spatial resolution was used for simulation of wave fields in 1966–2100. Regional climate projection EUR-11 assuming the RCP4.5 greenhouse gas scenario was used as wind forcing. In addition, using a site-dependently calibrated fetch-based wave model, a set of semi-realistic scenario calculations was obtained by modifying the baseline wind input data in order to investigate the reaction of wave climates and coastal developments. For coastal change, past developments in the shoreline and accumulation-erosion areas were tracked using repeated GPS measurements and GIS-overlaid cartographic and photographic material. The projections showed spatially and temporally varying wave fields and a slight overall increase, which corresponds to increased south-westerly winds. Depending on exposition, the wave climates would change differently even within a single semi-enclosed sea. Using the previously established empirical relationships between wave parameters and shoreline changes, we predict that erosion will probably increase in transitional zones while accumulation increases within bays. Sea-level rise and shortening of the sea-ice duration will probably have a remarkable contribution.

Description: The Baltic Sea is a severely eutrophicated sea-area where intense shipping as an additional nutrient source is a potential contributor to changes in the ecosystem. The impact of the two most important shipborne nutrients, nitrogen and phosphorus, on the overall nutrient-phytoplankton-oxygen dynamics in the Baltic Sea was determined by using the coupled physical and biogeochemical model system General Estuarine Transport Model–Ecological Regional Ocean Model (GETM-ERGOM) in a cascade with the Ship Traffic Emission Assessment Model (STEAM) and the Community Multiscale Air Quality (CMAQ) model. We compared two nutrient scenarios in the Baltic Sea: with (SHIP) and without nutrient input from ships (NOSHIP). The model uses the combined nutrient input from shipping-related waste streams and atmospheric depositions originating from the ship emission and calculates the effect of excess nutrients on the overall biogeochemical cycle, primary production, detritus formation and nutrient flows. The shipping contribution is about 0.3% of the total phosphorus and 1.25–3.3% of the total nitrogen input to the Baltic Sea, but their impact to the different biogeochemical variables is up to 10%. Excess nitrogen entering the N-limited system of the Baltic Sea slightly alters certain pathways: cyanobacteria growth is compromised due to extra nitrogen available for other functional groups while the biomass of diatoms and especially flagellates increases due to the excess of the limiting nutrient. In terms of the Baltic Sea ecosystem functioning, continuous input of ship-borne nitrogen is compensated by steady decrease of nitrogen fixation and increase of denitrification, which results in stationary level of total nitrogen content in the water. Ship-borne phosphorus input results in a decrease of phosphate content in the water and increase of phosphorus binding to sediments. Oxygen content in the water decreases, but reaches stationary state eventually.