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Indicator Specification
Accelerated nutrient flow into the sea (mostly from agricultural fertilisers) in combination with warming water temperatures can lead to large phytoplankton blooms and subsequent increases in primary production (a process called eutrophication). When these organisms sink to the sea floor, oxygen is utilised in their decomposition. If mixing within the water column cannot supply enough oxygen to the sea floor, this can lead to oxygen reduction (hypoxia) to levels that severely limit biological activity and ultimately to complete oxygen depletion (anoxia).
Most organisms, including marine organisms, require oxygen for their metabolism. Therefore, lower oxygen concentrations in seawater affect the physiology, composition and abundance of species. Rising water temperatures will have knock-on effects on a number of different chemical processes in the marine environment. For example, as the temperature rises, oxygen becomes less soluble in water, resulting in lower oxygen concentrations; at the same time, the oxygen demand for metabolism increases. Insufficient oxygen supply to organisms will eventually have knock-on effects on productivity, species interactions and community composition at the ecosystem level.
Oxygen depletion can occur episodically (less than once per year), periodically (several times per year for short periods) and seasonally (each summer), and eventually it can become persistent. The Baltic Sea has the largest dead zone in the world, which includes large areas of persistent oxygen depletion. Oxygen-depleted areas are an example of how one type of anthropogenic pressure, nutrient input causing eutrophication, is exacerbated by climate change (here increasing temperature) through multiple different linkages with biology, from cellular levels to community and ecosystem levels. For example, land-based nutrient enrichment can lead to a redistribution in the vertical distribution of primary production. Such increased nutrient input can increase primary production in the surface layer, where the oxygen produced can be exchanged with the atmosphere. The organic material produced will sink through the pycnocline (i.e. the ocean layer with a stable density gradient, which hinders vertical transport) using oxygen as it decomposes. At the same time, when primary production occurs below the pycnocline, the oxygen produced will stay in the bottom layer. As climate change influences stratification parameters, and consequently the depth of the pycnocline, it could influence light availability for primary production in the deeper layer, possibly decreasing oxygen production. In this case, the interaction between climate change and eutrophication can have impacts on biodiversity, plankton communities and oxygen conditions. Oxygen depletion may also interact with other anthropogenic stressors in affecting marine ecosystems and fisheries, such as overfishing or the introduction of invasive species.
In April 2013, the European Commission (EC) presented the EU Adaptation Strategy Package. This package consists of the EU Strategy on adaptation to climate change (COM/2013/216 final) and a number of supporting documents. The overall aim of the EU Adaptation Strategy is to contribute to a more climate-resilient Europe.
One of the objectives of the EU Adaptation Strategy is Better informed decision-making, which will be achieved by bridging the knowledge gap and further developing the European climate adaptation platform (Climate-ADAPT) as the ‘one-stop shop’ for adaptation information in Europe. Climate-ADAPT has been developed jointly by the EC and the EEA to share knowledge on (1) observed and projected climate change and its impacts on environmental and social systems and on human health, (2) relevant research, (3) EU, transnational, national and subnational adaptation strategies and plans, and (4) adaptation case studies.
Further objectives include Promoting adaptation in key vulnerablesectors through climate-proofing EU sector policies and Promoting action by Member States. Most EU Member States have already adopted national adaptation strategies and many have also prepared action plans on climate change adaptation. The EC also supports adaptation in cities through the Covenant of Mayors for Climate and Energy initiative.
In September 2016, the EC presented an indicative roadmap for the evaluation of the EU Adaptation Strategy by 2018.
In November 2013, the European Parliament and the European Council adopted the 7th EU Environment Action Programme (7th EAP) to 2020, ‘Living well, within the limits of our planet’. The 7th EAP is intended to help guide EU action on environment and climate change up to and beyond 2020. It highlights that ‘Action to mitigate and adapt to climate change will increase the resilience of the Union’s economy and society, while stimulating innovation and protecting the Union’s natural resources.’ Consequently, several priority objectives of the 7th EAP refer to climate change adaptation.
No targets have been specified.
Scientifically reported accounts of eutrophication-associated dead zones have been used to produce an overview of the distribution of oxygen-depleted ‘dead zones’ in European seas.
Simulations using observed dissolved oxygen concentrations as input have been carried out to estimate oxygen bottom concentrations and ‘dead zone’ areas.
Not applicable
See under "Methodology".
In general, changes related to the physical and chemical marine environment are better documented than biological changes. Observations of dissolved oxygen concentrations began around 1900. Since the 1960s, more regularly spaced measurements are undertaken and a more consistent data base for the assessment of the spatial extent of ‘dead zones’ is available.
No uncertainty has been specified
Work specified here requires to be completed within 1 year from now.
Work specified here will require more than 1 year (from now) to be completed.
For references, please go to https://www.eea.europa.eu/data-and-maps/indicators/ocean-oxygen-content or scan the QR code.
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