Impact of Climate Change on Ecological Quality Indicators and Biogeochemical Fluxes in the Baltic Sea: A Multi-Model Ensemble Study

• Published in: Ambio Vol. 41; no. 6; pp. 558 - 573
• Main Authors: Meier, H. E. Markus, Müller-Karulis, Bärbel, Andersson, Helén C, Dieterich, Christian, Eilola, Kari, Gustafsson, Bo G, Höglund, Anders, Hordoir, Robinson, Kuznetsov, Ivan, Neumann, Thomas, Ranjbar, Zohreh, Savchuk, Oleg P, Schimanke, Semjon
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer-Verlag 01.09.2012; Springer; Springer Netherlands; Springer Nature B.V
• Subjects: Anoxic waters; Atmospheric Sciences; Baltic Sea; Baltic States; Biogeochemical cycles; Biogeochemistry; climate; Climate Change; Climate models; denitrification; Earth and Environmental Science; Ecology; Emissions; Environment; Environmental Engineering/Biotechnology; Environmental impact; Environmental Management; Eutrophication; General circulation models; Geology; Greenhouse effect; Greenhouse gases; Hydrology; Hypoxia; Load; Marine biogeochemical cycles; Marine ecology; Modeling; Models, Theoretical; Nitrogen; Nitrogen fixation; Numerical modeling; Nutrient concentrations; Nutrient loading; Oceans and Seas; Oxygen; Phosphorus; Physical Geography; Phytoplankton; Phytoplankton - growth & development; Phytoplankton - isolation & purification; Pollution load; Precipitation; Runoff; Scenarios; Seas; Sediments; Simulation; Simulations; summer; Water depth; Water quality; Baltic Sea; Baltic States; Numerical modeling; Scenarios; Climate change; Marine biogeochemical cycles; Baltic Sea; Eutrophication
• ISSN: 0044-7447; 1654-7209; 1654-7209
• DOI: 10.1007/s13280-012-0320-3

Multi-model ensemble simulations using three coupled physical–biogeochemical models were performed to calculate the combined impact of projected future climate change and plausible nutrient load changes on biogeochemical cycles in the Baltic Sea. Climate projections for 1961–2099 were combined with four nutrient load scenarios ranging from a pessimistic business-as-usual to a more optimistic case following the Helsinki Commission′s (HELCOM) Baltic Sea Action Plan (BSAP). The model results suggest that in a future climate, water quality, characterized by ecological quality indicators like winter nutrient, summer bottom oxygen, and annual mean phytoplankton concentrations as well as annual mean Secchi depth (water transparency), will be deteriorated compared to present conditions. In case of nutrient load reductions required by the BSAP, water quality is only slightly improved. Based on the analysis of biogeochemical fluxes, we find that in warmer and more anoxic waters, internal feedbacks could be reinforced. Increased phosphorus fluxes out of the sediments, reduced denitrification efficiency and increased nitrogen fixation may partly counteract nutrient load abatement strategies.