Eutrophication of terrestrial ecosystems due to air pollution

Briefing Published 09 Dec 2016 Last modified 17 Oct 2019
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Eutrophication of terrestrial ecosystems due to air pollution

The Seventh Environment Action Programme (7th EAP) includes the objective of reducing the impact of air pollution on ecosystems and biodiversity, with the long-term aim of not exceeding critical loads and levels. Critical loads represent the upper limit of the levels of one or more air pollutants deposited to the Earth’s surface that an ecosystem can tolerate without being damaged. Currently, the most important impact of air pollution on ecosystems and biodiversity is eutrophication. The EU Thematic Strategy on Air Pollution includes, as a long-term objective for 2020, a 43 % reduction in the areas or ecosystems exposed to eutrophication as a result of air pollution, i.e. areas where eutrophication critical loads are exceeded.

The EU ecosystem area where the critical loads for eutrophication were exceeded decreased to 63 % in 2010. The area in exceedance is projected to further decrease to 54 % in 2020 for the EU, assuming that current legislation is fully implemented. The reduction in ecosystem areas exposed to eutrophication as a result of air pollution is estimated to be approximately 31 % between 2000 and 2020 and is below the 43 % reduction milestone suggested by the air pollution thematic strategy for this period. The improvements are primarily a result of reductions in eutrophying nitrogen emissions to the air. However, these emissions and, in particular, ammonia (NH3) and nitrogen dioxide (NO2) emitted from the agriculture and transport sectors, respectively, will remain significant contributors to eutrophication caused by air pollution. The eutrophication reduction objective will therefore not be met unless further specific and targeted mitigation measures are put in place. Dietary changes resulting in less meat and dairy farming and the reduced use of petrol and diesel in cars could also contribute to reductions.

Indicator

Indicator past trend


Selected objective to be met by 2020

Indicative outlook of the EU meeting the selected objective by 2020

Exposure of terrestrial ecosystems to eutrophication due to air pollution

EU

Green triangle: improving trend

EEA

Green triangle: improving trend

 

Reduce areas of critical load exceedance with
respect to eutrophication by 43 % from 2000 levels
— Air Pollution Thematic Strategy

 

Red circle: it is unlikely that the objective will be met by 2020

The area where ecosystems are exposed to eutrophication because of excess atmospheric nitrogen deposition has decreased. According to a scenario assuming that current legislation is fully implemented, it will, nevertheless, fall short of the 2020 objective

For further information on the scoreboard methodology please see Box I.1 in the EEA Environmental indicator report 2016

Setting the Scene

The 7th EAP (EU, 2013) includes the objective of reducing the impact of air pollution on ecosystems and biodiversity, with the long-term aim of not exceeding critical loads and levels. Currently, the most important impact of air pollution on ecosystems and biodiversity is eutrophication caused by airborne nitrogen pollution. Excessive atmospheric deposition of nitrogen to ecosystems results in loss of sensitive species, increased growth of species that benefit from high nutrient levels, changes to habitat structure and function, the homogenisation of vegetation types, etc.

Policy targets and progress

The EU Thematic Strategy on Air Pollution includes an objective for 2020, relative to 2000, of a 43 % reduction in areas or ecosystems exposed to eutrophication, i.e. areas where eutrophication critical loads are exceeded (EC, 2005a). The reference measure for this objective is the area in exceedance in 2000 (EC, 2005b). This is in line with the long-term objective of not exceeding critical loads.  

In 2000, the area of ecosystems where the critical load was exceeded was about 78 % of the total in the EU Member States (approximately 60 % in all 33 EEA member countries for which data were available, including the 28 EU Member States) and decreased in 2010 to 63 % in the EU (55 % in all 33 EEA member countries). Assuming that current legislation is fully implemented, the area in exceedance is projected to be 54 % in the EU (48 % in all 33 EEA member countries) in 2020 (EEA, 2015). The reduction is approximately 31 % for the EU, as well as for all the 33 EEA member countries, between 2000 and 2020, which is below the 43 % reduction milestone suggested by the air pollution thematic strategy for this period.

Nevertheless, as illustrated in Figure 1, the magnitude (though not the area) of the exceedance is projected to reduce considerably in most areas, except for a few ‘hot spot’ areas, particularly in Belgium, Germany and the Netherlands, as well as in northern Italy. The risk of eutrophication increases slightly when only Natura 2000 protected areas are addressed (EEA, 2014). 

Figure 1. Exposure of ecosystems to eutrophication – area and magnitude of exceedance in 2000 and 2020

Source: CCE (Coordination Centre for Effects), UNECE.

Note: The maps show areas where critical loads for eutrophication of freshwater and terrestrial habitats are exceeded

The main sources of eutrophication are emissions of nitrogen compounds to the atmosphere. Nitrogen oxide (NOx) emissions for the EU decreased by approximately 43 % between 2000 and 2014 (EEA, 2016a). This reduction has been primarily due to the introduction of three-way catalytic converters for cars. However, emission reductions from modern vehicles have not been as large as was originally anticipated. Standard diesel vehicles, for example, can emit up to seven times more NOx in real‑world conditions than in official tests (EEA, 2016b).

NH3 emissions have not fallen by as much. In 2014, they had fallen by approximately 9 % compared with their value in 2000 for the EU. Agriculture dominates emissions of NH3 (AIRS_PO3.2, 2016).1; they amount to approximately 95 % of total emissions in the EEA-33 region. Emissions primarily arise from the decomposition of urea in animal wastes and uric acid in poultry wastes.

A key driver behind the observed reductions was the implementation of the National Emission Ceilings Directive (EU, 2001), which regulates, inter alia, emissions of the eutrophying air pollutants NOx and NH3. However, eutrophying emissions not only from the agriculture and road transport sectors but also from shipping and air travel have been and will remain significant contributors to eutrophication caused by air pollution.

Further reductions in eutrophying air pollutant emissions are expected, inter alia, as a result of the 2012 amended Gothenburg Protocol, which sets air pollutant emission ceilings for 2020 (UNECE, 2012). Nevertheless, as illustrated by the results of the current legislation scenario (Figure 1), the decreases anticipated for 2020 are not expected to contribute sufficiently to reductions in the ecosystem area exposed to excess nitrogen deposition and affected by eutrophication. In 2020, more than 50 % of the ecosystem areas are expected to be at risk of eutrophication in the EU.

The 2020 thematic strategy objective will therefore not be met unless additional measures to mitigate nitrogen emissions are introduced, through further specific and targeted (technical) measures, particularly in the agriculture and transport sectors. Dietary changes resulting in less meat and dairy farming and the reduced use of petrol and diesel in cars could also contribute to reductions.

Country level information

Figure 2 shows the percentage of the area by country where the critical loads for eutrophication were exceeded in 2010 and the areas where exceedance is expected in 2020. Although a decrease is predicted by 2020, if current legislation is implemented, the area showing exceedance will be above 50 % in most countries (see bars). Extremely high magnitudes of exceedance can be found in Denmark, Hungary, Luxembourg, the Netherlands and Switzerland, caused by high deposition rates and/or ecosystems that are very sensitive to an excess supply of nitrogen from the atmosphere (see dots), for example nutrient-poor grasslands.  

Figure 2. The ecosystem area at risk of eutrophication and the magnitude of exceedance in each country

Figure 2. The ecosystem area at risk of eutrophication and the magnitude of exceedance in each country

Note: AAE is the average accumulated exceedance, showing the magnitude of exceedance in equivalents (mol nitrogen/ha per year). The data are based on the revised Gothenburg Protocol emission reduction agreements of 2012 (assuming for the  2020 scenario that current legislation is fully implemented). Data for Serbia and Montenegro are presented as aggregated data.

Outlook beyond 2020

The updated air pollution strategy proposed by the European Commission in late 2013 aims to achieve a situation in which the EU ecosystem area exceeding critical loads for eutrophication is reduced by 35% by 2030, relative to 2005 (EC, 2013). This target would not be met if only current legislation was fully implemented. In the EU, the area at risk of eutrophication is projected to decrease only slightly by 2030. The 35 % reduction target would be met in 2030 if the maximum number of technically feasible reduction measures was implemented (EEA, 2015).

As part of the air pollution strategy package, the European Commission has put forward a revised National Emission Ceilings (NEC) Directive. This proposes more ambitious national commitments to reduce emissions, compared with the current Directive (EC, 2001), for the two eutrophying air pollutants, NOx and NH3, among other things. These new ceilings will be applicable from 2020 and 2030 and will contribute to the achievement of the objective of 35% by 2030.

Beyond 2030, a time horizon of 2050 has been proposed as an aspirational year in which to achieve Europe’s long-term objectives, i.e. that air pollution does not lead to unacceptable harm to human health and the environment. 

About the indicator

The indicator shows area and quantitative information for ecosystems where atmospheric nutrient nitrogen deposition is above the critical load. A critical load is a “quantitative estimate of an exposure to one or more pollutants, below which significant harmful effects on specified sensitive elements of the environment do not occur according to present knowledge” (UNECE, 2015). Deposition loads of eutrophying airborne pollutants above the critical loads are termed an 'exceedance'. 

Exposure in an ecosystem for which information on critical loads is available, is calculated as the average accumulated exceedance (AAE). The AAE is the area-weighted average of exceedances, accumulated over all sensitive habitats (or ecosystem points) defined in a grid cell.

Footnotes and references

CCE, 2016, ‘Coordination Centre for Effects’, a data centre under the Convention on Long-range Transboundary Air Pollution (CLRTAP) (http://wge-cce.org), accessed 28 October 2016.

EC, 2005a, Communication of 21 September 2005 from the Commission to the Council and the European Parliament ‘Thematic strategy on air pollution’ (COM(2005) 446 final of 21 September 2005) (http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=URISERV%3Al28159) accessed 25 May 2016.

EC, 2005b, COMMISSION STAFF WORKING PAPER Annex to the COMMUNICATION FROM THE COMMISSION TO THE COUNCIL AND THE EUROPEAN PARLIAMENT ‘Thematic strategy on air pollution’§(COM(2005) 446 final)§ (SEC(2005) 1132 (http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A52005SC1132) accessed 26 October 2016.

EC, 2013, ‘The Clean Air Policy Package’, adopted 18 December 2013 (http://ec.europa.eu/environment/air/clean_air_policy.htm) accessed 25 May 2016.

EEA, 2014, Effects of air pollution on European ecosystems, EEA Technical Report No 11/2014 (http://www.eea.europa.eu/publications/effects-of-air-pollution-on) accessed 25 May 2016.

EEA, 2015, ‘Exposure of ecosystems to acidification, eutrophication and ozone (CSI 005)’ (http://www.eea.europa.eu/data-and-maps/indicators/exposure-of-ecosystems-to-acidification-3/assessment-2), accessed 28 October 2016.

EEA, 2016a, ‘Emissions of the main air pollutants in Europe (CSI 040)’ (http://www.eea.europa.eu/data-and-maps/indicators/main-anthropogenic-air-pollutant-emissions/assessment-1) accessed 25 May 2016. 

EEA, 2016b, Explaining road transport emissions — A non-technical guide (http://www.eea.europa.eu/publications/explaining-road-transport-emissions) accessed 25 May 2016.

EU, 2001, Directive 2001/81/EC of the European Parliament and of the Council of 23 October 2001 on national emission ceilings for certain atmospheric pollutants (OJ L 309, 27.11.2001, p. 22–30) (http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=celex%3A32001L0081) accessed 13 February 2015.

EU, 2013, Decision No 1386/2013/EU of the European Parliament and of the Council of 20 November 2013 on a General Union Environment Action Programme to 2020 ‘Living well, within the limits of our planet’ (OJ L 354, 28.12.2013, p. 171–200) (http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32013D1386) accessed 25 May 2016.

UNECE, 2012, ‘The 1999 Gothenburg protocol to abate acidification, eutrophication and ground-level ozone’, United Nations Economic Commission for Europe (http://www.unece.org/env/lrtap/multi_h1.html) accessed 25 May 2016.

UNECE, 2015, Manual on methodologies and criteria for modelling and mapping critical loads and levels and air pollution effects, risks and trends, United Nations Economic Commission for Europe, International Cooperative Programme on Modelling and Mapping (http://icpmapping.org/Mapping_Manual) accessed 25 May 2016.


AIRS briefings

1.         AIRS_PO3.2, 2016, Air pollutant emissions

Environmental indicator report 2016 – In support to the monitoring of the 7th Environment Action Programme, EEA report No30/2016, European Environment Agency

Related content

Based on indicators

Emissions of the main air pollutants in Europe Anthropogenic emissions of the main air pollutants decreased significantly in most EEA-33 member countries between 1990 and 2013: Nitrogen oxides (NO x ) emissions decreased by 49 % (54 % in the EU-28); Sulphur oxides (SO x ) emissions decreased by 80 % (87 % in the EU-28); Non-methane volatile organic compounds (NMVOC) emissions decreased by 57 % (59 % in the EU-28); Ammonia (NH 3 ) emissions decreased by 15 % (27 % in the EU-28); and Fine particulate matter (PM 2.5 ) emissions decreased by 34 % (34 % in the EU-28). The EU-28 met its continuing obligation to maintain emissions of NO x , SO x , NH 3  and NMVOC below legally binding targets as specified by the National Emission Ceilings Directive (NECD). However, a number of individual Member States reported emissions above their NECD emission ceilings: six for NO X (Austria, Belgium, France, Germany, Ireland and Luxembourg), six for NH 3 (Austria, Denmark, Finland, Germany, Netherlands and Spain) and three for NMVOCs (Denmark, Germany and Ireland). There are no emission ceilings for primary PM 2.5 . Three additional EEA member countries have emission ceilings for 2010 set in the Gothenburg Protocol under the 1979 UNECE Convention on Long-range Transboundary Air Pollution (Liechtenstein, Norway and Switzerland). Liechtenstein reported emissions above their NO x ceiling. Liechtenstein and Norway reported emissions above their NH 3 ceiling. Emissions reduction commitments for 2020 have been set under the 2012 amended Gothenburg Protocol for NO x , SO 2 , NMVOC, NH 3 , and PM 2.5 . The EU-28 as a whole is on track to meet its reduction commitments.
Exposure of ecosystems to acidification, eutrophication and ozone In the EU-28 countries, the ecosystem area where acidification critical loads were exceeded decreased from 43% in 1980 to 7% in 2010 (it also decreased by 7% across all EEA member countries). There remain some areas where the EU's interim objective for reducing acidification, as defined in the National Emission Ceilings Directive, has not been met.  The EU28 ecosystem area, where the critical loads for eutrophication were exceeded, peaked at 84% in 1990 and decreased to 63% in 2010 (55% in EEA member countries). The area in exceedance is projected to further decrease to 54% in 2020 for the EU28 (48% in EEA member countries), assuming current legislation is implemented. The magnitude of the exceedances is projected to reduce considerably in most areas, except for a few 'hot spot' areas in western France and the border areas between the Belgium, Germany and the Netherlands as well as in northern Italy. Only 4% of the EU-28 ecosystem area (3% in EEA member countries) is still projected to be in exceedance of acidification critical loads in 2020 if current legislation is fully implemented. The eutrophication reduction target set in the updated EU air pollution strategy proposed by the European Commission in late 2013, will be met by 2030 if it is assumed that all maximum technically feasible reduction measures are implemented, but it will not be met by current legislation. Most of Europe's vegetation and agricultural crops are exposed to ozone levels that exceed the long term objective specified in the EU Air Quality Directive. A significant fraction is also exposed to levels above the target value threshold defined in the directive. In 2012, the agricultural area exposed to concentrations above the target value threshold increased to 27% of the total area, representing an increase compared to the previous three years. With regard to forest ozone exposure, between 2004 and 2012, 60% or more of the forest area was exposed to concentrations above the critical level set by the UNECE Convention on Long Range Transboundary Air Pollution.  

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