Future projections of record-breaking sea surface temperature and cyanobacteria bloom events in the Baltic Sea
Aiming to inform both marine management and the public, coupled environmental-climate scenario simulations for the future Baltic Sea are analyzed. The projections are performed under two greenhouse gas concentration scenarios (medium and high-end) and three nutrient load scenarios spanning the range of plausible socio-economic pathways. Assuming an optimistic scenario with perfect implementation of the Baltic Sea Action Plan (BSAP), the projections suggest that the achievement of Good Environmental Status will take at least a few more decades. However, for the perception of the attractiveness of beach recreational sites, extreme events such as tropical nights, record-breaking sea surface temperature (SST), and cyanobacteria blooms may be more important than mean ecosystem indicators. Our projections suggest that the incidence of record-breaking summer SSTs will increase significantly. Under the BSAP, record-breaking cyanobacteria blooms will no longer occur in the future, but may reappear at the end of the century in a business-as-usual nutrient load scenario.
KeywordsClimate change Coastal seas Cyanobacteria Extremes Numerical modeling Sea surface temperature
The research presented in this study is part of the Baltic Earth program (Earth System Science for the Baltic Sea region, see http://www.baltic.earth) and was funded by the BONUS BalticAPP (Well-being from the Baltic Sea—applications combining natural science and economics) project which has received funding from BONUS, the joint Baltic Sea research and development programme (Art 185), funded jointly from the European Union’s Seventh Programme for research, technological development and demonstration and from the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS, Grant No. 942-2015-23). Additional support by FORMAS within the projects “Cyanobacteria life cycles and nitrogen fixation in historical reconstructions and future climate scenarios (1850–2100) of the Baltic Sea” (Grant No. 214-2013-1449) and “ClimeMarine” within the framework of the National Research Programme for Climate (Grant No. 2017-01949) is acknowledged. Further, we acknowledge Ann-Turi Skjevik who helped to identify the large filamentous nitrogen fixing cyanobacteria selected for the model evaluation and one anonymous reviewer and the Guest Editor, Dr. Jim Smart, who helped with constructive comments to improve the manuscript considerably.
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