Policy brief: Ocean acidification poses another threat to the Baltic Sea ecosystem

In the coming decades, ocean acidification is expected to become significant also in the Baltic Sea. For an already stressed ecosystem, it represents an additional pressure, and the cumulative effect of this and other environmental impacts can stress species and reduce biodiversity. Protecting the unique environment and future food production requires both significant reductions in carbon dioxide emissions and measures against eutrophication, overfishing and emissions of hazardous substances.

Recommendations

• Increase efforts to meet the carbon emission targets agreed at global and EU level.
• Accelerate action to reduce nutrient inputs from land and thus eutrophication, overfishing and emissions of hazardous substances.
• Promote a national and international ban on the discharge of scrubber washwater into the sea, which can cause severe acidification locally, and encourage the development of alternative fuels.
• Extend the acidification monitoring programmes in both space and time on a resolution that is relevant for species and ecosystems, and combine with biological observations.
• Promote biological research on Baltic species and ecosystems to evaluate their sensitivity to ocean acidification in combination with other local drivers.

It is now well recognised that today’s high greenhouse gas emissions are causing climate change and global warming. Less recognised is what is known as “the other carbon dioxide problem” – ocean acidification.

In the 1980s, acidification of soil, streams and lakes was one of the most high-profile environmental problems. Emissions of sulphur and nitrogen oxides from combustion processes in, for example, motor vehicles, power stations and heating plants gave rise to atmospheric deposition of sulphuric and nitric acid, popularly known as ’acid rain’, which had major impacts on lake and forest ecosystems. However, vastly improved treatment of emissions in the 1980s and 1990s, combined with the liming of lakes and rivers, led to a reduction of this type of acidification in the Baltic Sea region.

In recent years, another type of acidification has gained attention – global ocean acidification caused by massive carbon dioxide emissions. So far, these changes have been less evident in the Baltic Sea than in the open ocean, but in the long-term acidification will have an impact here too – posing yet another threat to the marine ecosystem.

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Policy brief: Ocean acidification poses another threat to the Baltic Sea ecosystem. Stockholm University Baltic Sea Centre. 7 February 2024. Policy brief.

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