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Exposure of ecosystems to acidification, eutrophication and ozone (CSI 005) - Assessment published Dec 2013

Indicator Assessmentexpired Created 02 May 2013 Published 20 Dec 2013 Last modified 05 Mar 2015, 02:35 PM
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This content has been archived on 02 Mar 2015, reason: Other (New version data-and-maps/indicators/exposure-of-ecosystems-to-acidification-3/assessment was published)

Key messages

    Eutrophication
    The magnitude of the risk of ecosystem eutrophication and its geographical coverage has diminished only slightly over the years. The predictions for 2010 and 2020 indicate that the risk is still widespread over Europe. This is in conflict with the EU's long-term objective of not exceeding critical loads of airborne acidifying and eutrophying substances in sensitive ecosystem areas (National Emission Ceilings Directive, 6th Environmental Action Programme, Thematic Strategy on Air Pollution).

    Acidification
    The situation has considerably improved and it is predicted to improve further. The interim environmental objective for 2010 (National Emission Ceilings Directive) will most likely not be met completely. However, the European ecosystem areas where the critical load will be exceeded is predicted to have declined by more than 80 % in 2010 with 1990 as a base year. By 2020, it is expected that the risk of ecosystem acidification will only be an issue at some hot spots, in particular at the border area between the Netherlands and Germany.

    Ozone

    Most vegetation and agricultural crops are exposed to ozone levels exceeding the long term objective given in the EU Air Quality Directive. A significant fraction is also exposed to levels above the 2010 target value defined in the Directive. Compared to 2009, the ozone indicators show a mixed behavior  Averaged over all rural background stations, the concentration relevant for the exposure of crops is slightly higher. However, the agricultural area exposed to concentrations above the target value did not increase in 2009 and 2010 compared to previous years, but the area exposed to levels between 12 000 and 18 000 (µg/m3).hour is larger than in the previous years. With respect to the exposure of forests, the concentrations are similar compared to previous years.

    The effect-related concentrations, addressing exposure of crops to ozone over several summer months, show large year-to-year variations. Over the period 1996-2010 there is a tendency to increased exposure until 2006; and a tendency to decreasing levels after 2006. However, due to the large year-to-year variations, this development has not proven to be statistically significant.

    What progress is being made towards the targets for reducing the exposure of ecosystems to acidification, eutrophication and ozone?

    Exceedance of critical loads for eutrophication due to the deposition of nutrient nitrogen in 2000

    Note: The results were computed using the 2008 Critical Loads database hosted by the Coordination Centre for Effects (CCE).

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    Exceedance of critical loads for eutrophication due to the deposition of nutrient nitrogen in 2010

    Note: The results were computed using the 2008 Critical Loads database hosted by the Coordination Centre for Effects (CCE).

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    Exceedance of critical loads for eutrophication due to the deposition of nutrient nitrogen in 2020 under current legislation to reduce national emissions

    Note: The results were computed using the 2008 Critical Loads database hosted by the Coordination Centre for Effects (CCE).

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    Exceedance of critical loads for eutrophication due to the deposition of nutrient nitrogen in 2020 assuming a maximum feasible reductions scenario

    Note: The results were computed using the 2008 Critical Loads database hosted by the Coordination Centre for Effects (CCE).

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    Exceedance of critical loads for acidification by deposition of nitrogen and sulphur compounds in 2000

    Note: The results were computed using the 2008 Critical Loads database hosted by the Coordination Centre for Effects (CCE).

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    Exceedance of critical loads for acidification by deposition of nitrogen and sulphur compounds in 2010

    Note: The results were computed using the 2008 Critical Loads database hosted by the Coordination Centre for Effects (CCE).

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    Exceedance of critical loads for acidification by deposition of nitrogen and sulphur compounds in 2020 assuming a Maximum Feasible Reductions scenario

    Note: The results were computed using the 2008 Critical Loads database hosted by the Coordination Centre for Effects (CCE).

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    Exceedance of critical loads for acidification by deposition of nitrogen and sulphur compounds in 2020 under Current Legislation to reduce national emissions

    Note: The results were computed using the 2008 Critical Loads database hosted by the Coordination Centre for Effects (CCE).

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    Exposure of agricultural area to ozone (exposure expressed as AOT40 in (μg/m³).h) in EEA member countries

    Note: Exposure of agricultural area to ozone (exposure expressed as AOT40 in (μg/m3).hour) in EEA member countries . In the Air Quality Directive (2008/50/EC) the target value for protection of vegetation is set to 18000 (μg/m3).h while the long-term objective is set to 6000 (μg/m3).hour. Until 2006 Iceland, Norway Switzerland and Turkey have not been included in the analyses due to lack of detailed land cover data and/or rural ozone data, in 2007 Switzerland and Turkey are not included; since 2008 only Turkey is not included

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    Rural concentration map of the ozone indicator AOT40 for crops, year 2010

    Note: AOT40 for crops are vegatation exposure related indicators and are based on rural background station observation only.

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    Exposure of forest area to ozone (exposure expressed as AOT40 in (mg/m³).h) in EEA member countries

    Note: Please consider that since 2004 a growing number of member countries has been included. In 2004 Bulgaria, Greece, Iceland, Norway, Romania, Switzerland, and Turkey have not been includedwere added. In For 2005/2006 Iceland, Norway Switzerland and Turkey are were still excluded in the analyses due to lack of detailed land cover data and/or rural ozone data. In 2007 Switzerland and Turkey are were not included. Since 2008 only Turkey is has not beennot included. Calculations of forest exposure are not available for year prior to 2004.

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    Rural concentration map of the ozone indicator AOT40 for forest in 2010

    Note: The gradient of the AOT40f values is similar to those of the AOT40c for crops: relative low in northern Europe, and the highest values observed in the countries around the Mediterranean. The critical level is met in north Scandinavia, Ireland, part of the UK and in the coastal regions of the Netherlands (total forested area with concentrations below the critical level is 22 % of a total area of 1.44 million km2). In south Europe levels may be as high as 4-5 times above the critical level.

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    Critical loads for nutrient nitrogen
    The EU has a long-term objective of not exceeding critical loads for nutrient nitrogen. Excess inputs of nitrogen to sensitive ecosystems may cause eutrophication and nutrient imbalances. The critical load of nutrient nitrogen is defined as the highest atmospheric deposition of nitrogen compounds below which harmful effects in ecosystem structure and function do not occur, according to present knowledge. In 2000 rather large areas show high exceedances of critical loads for nutrient nitrogen, especially in the western part of Europe, following the coastal regions from north-western France to Denmark. In southern Europe high exceedances are only found in northern Italy.

    The predictions for 2010 and 2020 indicate that the risk of exceedances is high irrespective of whether we assume that the current policies and measures to reduce eutrophying nitrogen emissions will be fully implemented (the current legislation CLE scenario) or that all technically and economically feasible additional policies are applied (the maximum feasible reduction MFR scenario).

    More specifically, the area with exceedances above 1200 eq ha-1a-1 in 2010 hardly changes under the CLE scenario in 2020, while exceedances in this highest range do not occur according to the MFR scenario (see Figure 4). However, in the latter case still broad areas in Europe remain at risk of eutrophication and negative changes in nutrient balances. In these areas exceedances that range from 200 to 1 200 eq ha-1a-1 are predicted (see the border area between the Netherlands and Germany, in particular).

    Critical loads for acidification
    The EU has a long-term objective of not exceeding critical loads for acidity in order to protect Europe's ecosystems from acidification. The critical load of sulphur and nitrogen acidity is defined as the highest deposition of acidifying compounds that will not cause chemical changes leading to long-term harmful effects on ecosystem structure and function.

    In addition to the long-term objective, the EU has a 2010 interim environmental objective to reduce areas where critical loads are exceeded by at least 50 % in each grid cell for which critical loads exceedances are computed, compared with the 1990 situation. The exceedances of critical loads for acidification caused by the deposition of air pollutants in 1990, 2000, 2010 (current legislation scenario; CLE) and 2020 (CLE as well as maximum feasible reduction scenarios, MFR) were calculated. 84 % of the grid cells with critical loads exceedances in 1990 show a decline in exceeded area of more than 50 % by 2010. Though the interim environmental objective has strictly speaking not been met, the improvements are considerable.

    Figures 5-8 show that in 2000 large areas with exceedances (i.e. higher than 1 200 eq ha-1a-1, shaded red) are mostly located in Belgium, Germany, the Netherlands and Poland. For the CLE scenario, the size of the area where critical loads are exceeded is considerably reduced in 2020. The MFR scenario shows that many areas in Europe will no longer be at risk of acidification in 2020 if all technically and economically feasible additional policies are also implemented. Nevertheless, high exceedance peaks between 700 and 1 200 eq ha-1a-1 would still be expected for ecosystems in the Netherlands.

    Ozone

    The EU has an objective for protecting vegetation from high ozone concentrations, accumulated over the growing season (defined as the summer months May to July). The target value for 2010 is 18 000 (µg/m3).hour [1]. The long term objective is 6 000 (µg/m3).h.

    This target is exceeded in a substantial fraction of the agricultural area in EEA-32 member countries (excluding Turkey). In 2010, this is the case in about 21 % of a total area of 2.054 million km2. Exceedances of the target values have notably been observed in southern and eastern Europe, see Figure 10. The long-term objective is met in 15 % of the total agricultural area, mainly in Ireland, Iceland, United Kingdom, Scandinavia and the Baltic States.

    In 2003, the meteorological conditions were very favorable for ozone formation resulting in exceptional high concentrations. Year 2004 was a less exceptional year and substantial lower ozone levels, similar to the levels in 2001/2002, were observed. In 2005 ozone concentrations were higher than in 2004 but the high levels of 2003 were not reached. The average ozone concentrations in 2006 were only slightly higher than in 2005. However, June and July 2006 were characterized by a large number of ozone episodes [2] resulting in much higher AOT40 value compared to 2005. In 2007 levels are lower again, similar to the situation in 2004. In 2008 ozone levels showed a general increase. Compared to 2009, the AOT40 values in 2010 were lower in southern Europe, in particular in the Balkan region.

    The data show that the target value set in the Air Quality Directive for 2010 was not met in the whole EU-27. Furthermore, it is expected that exposure of vegetation to ozone concentrations in the next decade will remain well above the long-term objective despite emission reductions of anthropogenic ozone precursor pollutants through EU legislation (National Emission Ceilings Directive, NECD) and UNECE protocols (under the Convention on Long Range Transboundary Air Pollution, LRTAP).

    The NECD contains two interim objectives (to be met in 2010) concerning vegetation-related ozone exposure. The first of these is a one third reduction objective for 2010 in all grid cells compared to the 1990 situation, while the second addresses the absolute concentration limits to be attained by 2010. Based on model calculation this objective has been met in the European Union except in parts of Spain and Portugal. The second objective – no exceedance of a critical level of 20 (mg/m3).h  during the summer season –  is clearly not achieved in most of Europe. An evaluation of the two objectives on the basis of measurements is hardly possible, due to the lack o f monitoring stations in the early nineties. However, the limited number of available time series suggests a less optimistic situation than the assessment based on model calculations (EEA, 2012).

    In addition to the EU target value, a critical level for the protection of forest has been defined under the LRTAP Convention. This critical level relates to the accumulated sum during the summer (April-September) and is set to 10 000 (μg/m3).h. Figure 12 shows the 2010 results for the AOT40 for forests (AOT40f). The gradients of the AOT40f values are similar to those of the AOT40c for crops: relative low in northern Europe, and the highest values observed in the countries around the Mediterranean. The critical level is met in Scandinavia, Ireland, part of the UK and in the coastal regions of the Netherlands (total forested area with concentrations below the critical level is 35% of a total area of 1.44 million km2). In southern Europe, levels may be as high as 4-5 time above the critical level, see Figure 12.

    Figure 11 summarizes the exposure of forested areas in 2010; during the period 2004 to 2010 large variations are observed. While in 2004 and 2006 almost all forests were exposed to levels exceeding the critical level, in 2007 40% was exposed to levels lower than the critical level. Similar to the AOT40 for crops no significant up- or downward trend could be detected.

    [1] Microgram/m3 can be abbreviated as 'µg/m3' and hours as 'h'. To avoid large numbers, the AOT40 is expressed in (mg/m3).hour; 1 (mg/m3).hour equals 1 000 (µg/m3).hour.

    [2] See: EEA (2007) Air pollution by ozone in Europe in summer 2006. EEA Technical report 5/2007.

    Which areas in Europe remain most affected by eutrophication, acidification and ground-level ozone?

    Percentage of ecosystem area at risk of eutrophication for EEA Member Countries and EEA Cooperating Countries in 2010 for a current legislation (CLE) scenario

    Note: The results were computed using the 2008 Critical Loads database. Deposition data was made available by the LRTAP Convention EMEP Centre for Integrated Assessment Modelling (CIAM) at the International Institute for Applied Systems Analysis (IIASA) in autumn 2007.

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    Percentage of ecosystem area at risk of eutrophication for EEA Member Countries and EEA Cooperating Countries in 2020 for a CLE scenario

    Note: The results were computed using the 2008 Critical Loads database. Deposition data was made available by the LRTAP Convention EMEP Centre for Integrated Assessment Modelling (CIAM) at the International Institute for Applied Systems Analysis (IIASA) in autumn 2007.

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    Percentage of ecosystem area at risk of eutrophication for EEA Member Countries and EEA Cooperating Countries in 2020 for a maximum feasible reduction (MFR) scenario

    Note: The results were computed using the 2008 Critical Loads database. Deposition data was made available by the LRTAP Convention EMEP Centre for Integrated Assessment Modelling (CIAM) at the International Institute for Applied Systems Analysis (IIASA) in autumn 2007.

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    Percentage of ecosystem area at risk of acidification for EEA Member Countries and EEA Cooperating Countries in 2010 for a current legislation (CLE) scenario

    Note: The results were computed using the 2008 Critical Loads database. Deposition data was made available by the LRTAP Convention EMEP Centre for Integrated Assessment Modelling (CIAM) at the International Institute for Applied Systems Analysis (IIASA) in autumn 2007.

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    Percentage of ecosystem area at risk of acidification for EEA Member Countries and EEA Cooperating Countries in 2020 for a CLE scenario

    Note: The results were computed using the 2008 Critical Loads database. Deposition data was made available by the LRTAP Convention EMEP Centre for Integrated Assessment Modelling (CIAM) at the International Institute for Applied Systems Analysis (IIASA) in autumn 2007.

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    Percentage of ecosystem area at risk of acidification for EEA Member Countries and EEA Cooperating Countries in 2020 for a maximum feasible reduction (MFR) scenario

    Note: The results were computed using the 2008 Critical Loads database. Deposition data was made available by the LRTAP Convention EMEP Centre for Integrated Assessment Modelling (CIAM) at the International Institute for Applied Systems Analysis (IIASA) in autumn 2007.

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    Percentage of natural ecosystem area at risk of acidification (left) and of eutrophication for the 32 EEA member countries and EEA cooperating countries in 2000 and for two emission scenarios: current legislation (CLE) in 2010 and 2020, maximum feasible r

    Note: Hettelingh J-P, Posch M, Slootweg J (eds.) (2008) Critical load, dynamic modelling and impact assessment in Europa: CCE Status Report 2008, Netherlands Environmental Assessment Agency.

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    Annual variation in the ozone AOT40 value for crops (May-July) in (μg/m³).h, 1996–2010

    Note: Average values over all rural stations which reported data over at least eleven years in the period 1996-2010. The black line corresponds to the 5-year averaged value. Variations over Europe in observed values is large, eighty percent of the observations falls with the red shaded area.

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    Agricultural area (in 1 000 km²) in EEA member countries for each exposure class

    Note: A data summary of agricultural area (in 1000 km²) for EEA countries for each exposure class is given in the table below. The total agricultural area in the EEA-32 member countries excluding Iceland, Norway, Switzerland and Turkey amounts to be 2.024 million km2; since 2007 Iceland and Norway are included in the analysis increasing the total agricultural area to 2042 million km2. Since 2008 data for Switzerland is available

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    Ozone

     

    Observed AOT40 concentrations for crops indicate increasing ecosystem exposure, but with large variation. Over the period 1996-2010, 285 rural background stations were providing valid data to AirBase during at least 11 years. At 37 % of the stations (106) the time series have a tendency to increase although at only 4 stations this increase is (based on a Mann-Kendal test) statistically significant. The remaining 179 stations show a downwards development in ozone levels, 18 of these stations show a statistically significant trend. 

    A data summary of agricultural area (in 1000 km2) for EEA countries for each exposure class is given in the table below. The total agricultural area in the EEA-32 member countries excluding Iceland, Norway, Switzerland and Turkey amounts to be 2.024 million km2. Since 2007, Iceland and Norway are included in the analysis, increasing the total agricultural area to 2.042 million km2. Since 2008 data for Switzerland is available.

    Indicator specification and metadata

    Indicator definition

    The indicator shows the ecosystem or crops areas at risk of exposure to harmful effects of ozone as a consequence of air pollution, and shows the state of change in acidification, eutrophication and ozone levels of the European environment. The risk is estimated by reference to the 'critical level' for ozone for each location, this being a quantitative estimate of the exposure to these pollutants below which significant and harmful effects do not occur in the long term at present knowledge.

    The fraction of agricultural crops that is potentially exposed to ambient air concentrations of ozone in excess of the EU target value and long-term objective set for the protection of vegetation is also shown.

    • Eutrophication and acidification
      Critical loads of acidity and of nutrient nitrogen are employed to describe exposure to acidification and to eutrophication for forests and semi-natural areas in Europe, including Natura 2000 sites. The area where the deposition of acidifying and eutrophying pollutants is in exceedance of critical loads provides also an indication of the extent of European ecosystem area which is at risk of damage to biodiversity. By analysing the change of exceedances over time (comparative static analysis) an indication of the effects of changing air pollutant emissions over time is obtained. The magnitude of the exceedance (deposition minus critical load) is an important input to the dynamic modelling of time delays in damage. Inversely, once critical loads are no longer exceeded, recovery may take some time as well. By including the risk to be met within a legislative target and year the distance from this target can be evaluated.
    • Ozone
      AOT40 is 'Accumulated ozone exposure over a threshold of 40 ppb'. The indicator shows the ecosystem or crop areas at risk of exposure to harmful levels of ozone as a consequence of air pollution. The risk is estimated by referring to the 'critical level' of ozone for sensitive areas. Thus, the indicator is a quantitative estimate of the exposure to ozone below which significant and harmful effects do not occur in the long term according to present knowledge.
      The fraction of agricultural crops that is potentially exposed to ambient air concentrations of ozone in excess of the EU target value set for the protection of vegetation is also shown.

    Units

    Eutrophication and acidification

    • Regions at risk: % of total sensitive ecosystem area
    • Critical loads/threshold, depositions, exceedance:
             - Acidifying equivalents (H+) per hectare and year (eq H+.ha-1.a-1)
             - Eutrophication equivalents (N) per hectare and year(eq N.ha-1.a-1)
    • Change over time: % of change compared to base year.

    Ozone

    • AOT40: means the sum of the differences between hourly concentrations greater than 80 µg/m3 (= 40 parts per billion) and 80 µg/m3 accumulated over all hourly values measured between 8.00 – 20.00 Central European Time. For crops the accumulation is from 1 May to 31 July. For forest the accumulation is over the summer period (1 April – 30 September).  each day ozone concentrations. AOT40 is expressed in (μg/m3).hour
    • Regions at risk: % of total agricultural area
    • Change over time: % of change compared to base year.
    • Percentage of the arable land in Europe potentially exposed to ambient air concentrations of ozone (O3) in excess of the EU target value set for the protection of vegetation.

    Policy context and targets

    Context description

    This indicator is relevant information for the EU's 6th Environmental Action Programme (6EAP) and the Thematic Strategy on Air Pollution. The 6EAP sets the long-term objective of not exceeding critical loads.
    A combined ozone, acidification and eutrophication abatement strategy has been developed by the European Commission, resulting in the National Emission Ceiling Directive (2001/81/EC) and the CAFE Thematic Strategy. In this legislation, target values have been set for air pollutant emissions causing acidification and eutrophication, as well as for ozone levels and for ozone precursor emissions. The EU legislation sets for ozone both a target value (to be met in 2010) and a long-term objective. This long-term objective is largely consistent with the long-term critical level of ozone for crops as defined in the UNECE LRTAP Convention protocols to abate acidification, eutrophication and ground level ozone.
    Within the LRTAP Convention there is a discussion whether a concentration-base or a flux-based critical level is the best indicator for the impact on ecosystems (see, for example, EMEP,2010). As the target value and long-term objective in air quality directive are concentration-based, the AOT40 has been chosen here as relevant parameter.

    Targets

    • National Emission Ceilings Directive 2001/81/EC, Article 5
      The aim of the directive is to 'limit emissions of acidifying and eutrophying pollutants and ozone precursors in order to improve the protection in the Community of the environment and human health against risks of adverse effects from acidification, soil eutrophication and ground-level ozone and to move towards the long-term objectives of not exceeding critical levels and loads… by establishing national emission ceilings, taking the years 2010 and 2020 as benchmarks National emission ceilings with interim environmental objectives for the Community as a whole...'.
      The following interim environmental objectives, for the Community as a whole, by 2010 has been set for acidification: The areas where critical loads are exceeded shall be reduced by at least 50 % (in each grid cell) compared with the 1990 situation.
      The interim environmental objective for vegetation-related ground-level ozone exposure is: By 2010 the ground-level ozone load above the critical level for crops and semi-natural vegetation (AOT40 = 3 ppm.hour) shall be reduced by one-third in all grid cells compared with the 1990 situation. In addition, the ground-level ozone accumulated concentration shall not exceed an absolute limit of 10 ppm.hour, expressed as an exceedance of critical accumulated concentration in any grid cell.

    • UNECE CLRTAP Gothenburg Protocol (1999)
      To abate acidification, eutrophication and ground level ozone it sets emission limits with target dates. Whilst environmental quality objectives are not specified, full attainment of emission targets is intended to bring an improvement in the state of the environment estimated at:
      1. Reduction in the European area with excessive levels of acidification from 93 million ha in 1990 to 15 million ha in 2010, and with excessive eutrophication from 165 million ha in 1990 to 108 million ha in 2010. The number of days with excessive ozone levels will be halved. The exposure of vegetation to excessive ozone levels will be 44 % less in 2010 compared to 1990.
      2. Long-term objective, atmospheric depositions will not exceed critical loads of acidity and critical loads of nutrient nitrogen.
    • Air Quality Directive (2008/50/EC)
      For the protection of vegetation to ozone exposure the Air Quality Directive defines:
      1. The target value for the protection of vegetation as AOT40-value (calculated from hourly values from May to July) of 18 (mg/m3).h, averaged over five years. This target value should be met in 2010.
      2. A long-term objective of 6 (mg/m3).h.

    Related policy documents

    Methodology

    Methodology for indicator calculation

    • Acidification and eutrofication
      Air emission data is reported annually by national authorities to UNECE/EMEP (Convention on Long-range Transboundary Air Pollution) and to the European Community. Reported data includes both newest estimates (two years in arrears) and recalculated emissions from previous years. Emission data is stored and verified at EMEP/CEIP (Centre on Emission Inventories and Projections) [1].
      Using these emissions, EMEP/MSC-W [2] calculates atmospheric transport of sulphur and nitrogen pollutants using the EMEP Unified Model at a spatial resolution of 50 x 50 km2 and according to modelled meteorological conditions adjusted towards observations.
      The Coordination Centre for Effects (CCE) has produced an update of the critical loads database in 2008 (Hettelingh et al., 2008) [3] for use in support of revisions of European air pollution agreements. In 2004 the CCE updated this database with national updates of critical loads (see below section on gap-filling where countries did not provide data). The CCE collaborates with IIASA (CIAM) [4] and EMEP to assess information on ecosystem specific deposition which the CCE then uses to compute and map exceedances in European natural areas including Natura 2000 areas.
      Nitrogen and sulphur deposition in each model grid-cell are used for calculation of the average accumulated exceedances of the critical loads, which is the area-weighted average of exceedances accumulated over all ecosystem points in an EMEP grid cell. The total area of ecosystems exposed to exceedances in a country is expressed as a percentage of the total country area. These areas are summed up to provide two estimates, one for the EU-27 Member States, and for one for a larger region comprising most countries that are Parties to the Convention on Long-range Transboundary Air Pollution (including the non-EU EEA member countries and the EEA cooperating countries).
    • Ozone
      According to the definition in the ozone directive, AOT40 values are calculated from hourly data measured between 08.00 and 20.00 CET at all rural background stations available in AirBase. For crops AOT40 is accumulated during the three month summer period (May-July); for forest accumulation is during the full summer (April-September). Only data series with more than 75 % valid data were considered.

      The AOT40 maps have been created by combining measurements data from the rural background stations combined with the results of the EMEP dispersion model [Fagerli et al 2004] altitude field and surface solar radiation in a linear regression model, followed by the interpolation of its residuals by ordinary kriging [see de Smet et al, 2009 and reference cited therein for more details]. As altitude dataset GTOPO30 (Global Digital Elevation Model) at a resolution of 30 x 30 arcsecond has been used [ESRI, Redlands, California, USA, 2005]. The solar radiation has been obtained from ECMWF [ECMWF: Meteorological Archival and Retrieval System (MARS). It is the main repository of meteorological data at ECMWF].  Kriging is a method of spatial statistics (see e.g. N. Cressie, Statistics for spatial data, New York, 1993) which makes use of spatial autocorrelation (the statistical relationship between the monitoring points expressed in the form of variograms). Kriging weights the surrounding measured values to derive an interpolation for each location. The weights are based (i) on the distance between the measured points and the interpolated point, (ii) on the overall spatial arrangement among the measured points. The type of kriging at its parameters (in particular the parameters describing the semivariogram) are chosen in order to minimize the RMS error.

      The AOT40 maps have been overlayed in a GIS with the land cover CLC2000 map. The resolution was 500 x 500 m2 to generate maps for the agricultural area at risk due to ozone exposure. Exposure of agricultural area (defined as the land cover level-1 class 2 Agricultural areas encompassing the level-2 classes 2.1 Arable land, 2.2 Permanent crops, 2.3 Pastures and 2.4 Heterogeneous agricultural areas) and forest areas (defined as the land cover level-2 class 3.1. Forests) have been calculated at the country-level.

      The temporal trends have been estimated using a Mann-Kendal statistical test. This test is particularly useful since missing values are allowed and the data need not to conform to any particular distribution. Moreover, as only the relative magnitudes of the data rather than their actual measured values are used, this test is less sensitive towards incomplete data capture and/or special meteorological conditions leading to extreme values.(see Gilbert, R.O., 1987. Statistical Methods for Environmental Pollution Monitoring. Van Nostrand Reinhold, New York).

     

    Methodology for gap filling

    • Acidification and eutrophication
      National submissions are used where available. For European countries which have never submitted national totals the CCE uses its European background critical load database (Hettelingh et al., 2004). Turkey has not been included in the analysis due to a not sufficient data basis for calculating critical loads.
    • Ozone
      In the AOT40-mapping Turkey has to be excluded due to the lack of reported measurements at rural background stations. In the exposure estimates Switzerland has only been included since 2008 onwards.

    Methodology references

    No methodology references available.

    Uncertainties

    Methodology uncertainty

    • Critical loads
      A comprehensive uncertainty analysis of the integrated assessment approach, including ecosystem effects (critical loads) was compiled by Suutari et al. (2001) [1].
    • Ozone
      The air quality data is officially submitted according to the Exchange of Information decision (Council Decision 97/101/EC). It is assumed that the air quality data has been validated by the national data supplier. Station characteristics and representativeness is often insufficiently documented, which may imply that stations that are not representative for background conditions have been included. Methodology uncertainty is given by uncertainty in mapping AOT40 based on the interpolation of point measurements at background stations. The mean interpolation uncertainty of the map of AOT40 for crops is estimated to be about 35 %.

    [1] Suutari, R., Amann, M., Cofala, J. Klimont, Z., Schöpp, W. and Posch, M. (2001): From Economic Activities to Ecosystem Protection in Europe – An Uncertainty Analysis of Two Scenarios of the RAINS Integrated Assessment Model: http://www.iiasa.ac.at/rains/reports.html

    Data sets uncertainty

    • Ozone
      Most data have been officially submitted to the Commission under the Exchange of Information Decision (and/or to EMEP under the UN ECE Convention). Air quality monitoring station characteristics and representativeness are often not well documented and coverage of territory and in time is incomplete. The different definition of AOT40-values (accumulation during 8.00 to 20.00 CET following the Ozone Directive versus accumulation during daylight hours following the definition in the NEC Directive) is expected to introduce minor inconsistencies in the data sets. The indicator as chosen provides information on the area for which monitoring information is available. Yearly changes in monitoring density will influence the total monitored area. Due to deficiencies in meta-information, the selection of background sites may include some non-background stations, probably leading to a slight underestimation of the indicator.

      The indicator is subject to year-to-year fluctuations as it is mainly sensitive to episodic conditions, and these depend on particular meteorological situations, the occurrence of which varies from year to year. For instance, the relatively favourable values for 1998 are largely due to unfavourable condition for ozone formation (in other words: '1998 was a bad summer'). 2003 was a hot 'high-ozone' summer in most of Europe. When averaging over Europe this meteorologically induced variation may be less, provided spatial data coverage is sufficient.

      In spite of a generally reasonable level of accuracy and precision of ozone measurements, the indicator is rather sensitive to the precision at the reference level (40 ppb or about 80 micrograms/m3), and to the accuracy of measured ozone levels. Moreover, the number of available data series varies considerably from year to year and for some years it is very low.

    Rationale uncertainty

    No uncertainty has been specified

    Data sources

    Generic metadata

    Topics:

    Air pollution Air pollution (Primary topic)

    Tags:
    eutrophication | soer2010 | csi | baseline | air pollution | forests | air | ozone | thematic assessments | aot40 | air quality | acidification
    DPSIR: State
    Typology: Performance indicator (Type B - Does it matter?)
    Indicator codes
    • CSI 005
    Dynamic
    Temporal coverage:
    1996-2010, 2020
    Geographic coverage:
    Albania, Austria, Belgium, Bosnia and Herzegovina, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, EU15, Belgium, Sweden, United Kingdom, Greece, Portugal, France, Finland, Spain, Germany, Italy, Austria, Denmark, Luxembourg, Ireland, Netherlands, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Macedonia (FYR), Malta, Montenegro, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, United Kingdom

    Contacts and ownership

    EEA Contact Info

    Michel Houssiau

    Ownership

    EEA Management Plan

    2012 2.0.1 (note: EEA internal system)

    Dates

    Frequency of updates

    Updates are scheduled once per year
    European Environment Agency (EEA)
    Kongens Nytorv 6
    1050 Copenhagen K
    Denmark
    Phone: +45 3336 7100