Impact of climate change on the Baltic Sea ecosystem over the past 1,000 years

• Published in: Nature climate change Vol. 2; no. 12; pp. 871 - 874
• Main Authors: Kabel, Karoline, Moros, Matthias, Porsche, Christian, Neumann, Thomas, Adolphi, Florian, Andersen, Thorbjørn Joest, Siegel, Herbert, Gerth, Monika, Leipe, Thomas, Jansen, Eystein, Sinninghe Damsté, Jaap S.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.12.2012; Nature Publishing Group
• Subjects: 704/106/413; 704/106/694; 704/158/2446; Anthropogenic factors; Climate Change; Climate Change/Climate Change Impacts; Earth and Environmental Science; Ecosystem models; Ecosystems; Environment; Environmental changes; Environmental impact; Environmental Law/Policy/Ecojustice; Global warming; Ice ages; letter; Marine; Nutrient loading; Oxygenation; Surface temperature; Surface water; Water temperature; ANE, Baltic Sea
• ISSN: 1758-678X; 1758-6798
• DOI: 10.1038/nclimate1595

Marked ecosystem changes in the Baltic Sea have been recorded in the sediments, but the reasons are not fully understood. Now an integrated study of high-resolution sediment records (of the past 1,000 years) in combination with an ecosystem modelling approach reveals that surface temperature changes strongly influence deepwater oxygenation. Climate change has a strong impact on ecosystem health, particularly in marginal seas 1 such as the Baltic, for example causing the spreading of anoxic areas (oxygen-free areas, the so-called dead zones) through strong feedbacks. Marked ecosystem changes in the Baltic Sea have been recorded in the sedimentary archive, but the reasons are not fully understood 2 , 3 . Here we report an integrated study of high-resolution sediment records (past 1,000 years) in combination with an ecosystem modelling approach, providing new insights into the functioning of the Baltic Sea ecosystem under natural and human-influenced climatic changes. Between the Little Ice Age and the Modern Warm Period the surface water temperatures reconstructed using TEX 86 palaeothermometry increased by ∼2 °C. Simultaneously, the anoxic areas in the Baltic Sea began to expand significantly as evident from the accumulation of laminated sediments. Ecosystem model simulations support our findings of widespread oxic areas during the Little Ice Age. Backed up by the modelling results that take into account anthropogenic-influenced nutrient load scenarios, our results provide evidence that surface temperature changes strongly influence deepwater oxygenation. This highlights the risk of a continued spreading of anoxic areas during scenarios of continued climate warming in the future.