Emissions to air

The national emission model includes four dimensions:

• Pollutants: The different gases/substances covered by the emission model
• Technical emission sources: Stoves, ships, vehicles, flares, biological and industrial processes
• Industry: Standard Industrial Classification (NACE)
• Commodity: Different energy commodities; solid fuels (for example coal and coke), liquid fuels (diesel oil, petrol, kerosene, heavy oil etc.), gases (natural gas, landfill gas etc.), biofuel (for instance fuel wood, wood waste, pellets) and waste (hazardous waste and other waste).

CO₂ equivalents:

• The various greenhouse gases cause atmospheric heating to different degrees. To have a consistent overview of the total effects from these gases, GWP (global warming potential) values are used. The GWP-value of a gas is defined as the greenhouse effect of one ton of the given gas compared to one ton of CO2. As a result, the unit we use to measure greenhouse gas emissions is called CO2-equivalents.

Substance and GWP value due to IPCC Fifth Assessment Report (AR5)

Acid equivalents

• Other polluting gasses are measured together in relation to their overall polluting effect. NH3 for example is considered a polluting gas because biological processes in the soil convert basic NH3 to an acid, which has a range of negative effects. The following factors are used to convert different polluting gases to acid equivalents (Potential Acid Equivalents)
  • NOx * 1/46
  • SO2 * 1/32
  • NH3 * 1/17

• International agreements consider each polluting gas separately, and not together as acid equivalents.

Ozone precursors

• Ozone precursors are pollutants that cause the formation of ozone in the atmosphere, also known as ground-level ozone, which acts as a greenhouse gas. Some of the most significant ozone precursors are:
  • Non-methane volatile organic compounds (NMVOC)
  • Nitrogen oxides (NOx)
  • Carbon monoxide (CO)

Environmental toxins

• Environmental toxins are a group of various organic and inorganic substances that are resistant to decomposition (persistent), and which both accumulate and have toxic effects in living organisms.

Heavy metals:

• Lead (Pb)
• Cadmium (Cd)
• Mercury (Hg)
• Copper (Cu)
• Chrome (Cr)

Other elements

• Arsenic (As)

POPs (Persistent Organic Pollutants)

• Polycyclic aromatic hydrocarbons (PAHs)
• Dioxins

Particulate matter

• TSP – total particulate matter (Total Suspended Particulates)
• PM10 - Particulate matter with a diameter of less than 10 micrometers
• PM2,5 - Particulate matter with a diameter of less than 2,5 micrometers

Standard Classifications in the published tables:

Classification of sources for emissions to air, national figures

Classification of substances emitted to air

Classification of Variant of SIC - Environmental accounts

Emissions to air from Norwegian economic activity has been revised for the industry classification 2007, which has been valid since 1. January 2009.

Standard Classifications in the reported tables:

NAMEA (NACE according to Quarterly National Accounts)

CRF - tables to UNFCCC

NFR - tables to UNECE

Name: Emissions to air
Topic: Nature and the environment

Division for Energy, Environmental and Transport Statistics

National figures

The statistics are published annually in two versions; in June, preliminary figures for the year T-1 are published. In November, a revised and more detailed version of the figures are published. At the same time, revised figures for all years back to 1990 are published if new information is available (e.g. changes in activity data, new emission figures,new methods, etc.).

Statistics Norway reports figures from the statistics to the following international organisations:

• The statistical office of the European union (Eurostat)
• The United Nations (UN) sub-organisations UNFCCC and UNECE
• EU

The reportings to UN an EU are administrated by the Norwegian Environment Agency

Collected and revised data are stored securely by Statistics Norway in compliance with applicable legislation on data processing.

Statistics Norway can grant access to the source data (de-identified or anonymised microdata) on which the statistics are based, for researchers and public authorities for the purposes of preparing statistical results and analyses. Access can be granted upon application and subject to conditions. Refer to the details about this at Access to data from Statistics Norway.

The purpose of these statistics is to present the total emissions from Norwegian territory, distributed by sources, industries and energy goods. The statistics also contribute to show the progress regarding the fulfilment of international environmental obligations and national emission targets. In addition, the statistics give information to media, schools, other institutions or organizations, and the public.

The first statistics on emission of CO2 were made in 1987. Since then, methodologies for estimating other emissions have been developed. The first pollutants to be added were methane and nitrous oxide, then later the fluoride gases SF6, PFCs, and HFCs. All calculations have been revised since they were first implemented.

The statistics are largely developed in order to fulfill the demands for reporting to the United Nations Convention on Climate Change (UNFCCC). The Norwegian Environment Agency, on behalf of the Ministry of Climate and Environment, is responsible for this reporting. The reported emission figures cover only Norwegian territory, including domestic air and sea traffic. When it comes to border traffic, i.e. fuel bought in Norway and used abroad, or bought abroad and used in Norway, it is assumed that the sizes are approximately the same. This does not apply to navigation and aviation.

The statistics can also provide figures on emissions from Norwegian economic activity, as defined in the national accounts. These figures include Norwegian international transport (aviation and navigation) and are used in the environmental accounts (NAMEA) and reports to Eurostat. As the delimitation is different, the emission figures from Norwegian territory and Norwegian economic activity will also differ.

The emission statistics are mainly based on calculations. The emission model is continuously being developed, as research on air emissions is evaluated regularly. New emission factors are taken into use, errors in the calculations are corrected, and other improvements in the emission model are implemented. These changes lead to new, revised and more consistent time series, and results that are published earlier are no longer valid.

The regular compilation of the statistics is financed by Statistics Norway, but development, improvements and special demands are to a great extent financed by the Norwegian Environment Agency.

The emission inventory and its basic statistics are mainly used for the following purposes:

1. International reporting

2. As a tool for public administration and the authorities

3. Research and education

4. Market, resource and environmental mapping

5. General information

International reporting is an important use of the official statistics. Figures from the emission inventory are being used by the Ministry of Climate and Environment and the Norwegian Environment Agency in reports to UNFCCC. These figures state whether Norway has reached its targets or not. Eurostat, OECD and others are given access to the figures via UNFCCC. The statistics are used to determine if Norway has reached its targets under Paris Agreement and other environmental agreements. Up to the end of 2022 Norway’s commitments were held under the Kyoto Protocol, while from 2023 onwards the commitments are held under the Paris Agreement. These statistics are also sent to Eurostat, OECD, and others who use the UNFCCC’s database. In addition, these statistics are used for yearly reporting to the UNECE (LRTAP/ Gothenburg Protocol).

The emission inventory is used by the authorities in environmental information documents, such as the Government's environmental policy, and in different SDIs: Sustainable Development Indicators.

Statistics Norway also makes use of the emission inventory to make forecasts/prognoses, and as a basis for economic analyses. NAMEA (National Accounts Matrix including Environmental Accounts) shows the connection between economic and environmental development.

Public and private institutions use the statistics in studies connected to emission technology, pollution, health and economy.

The emission inventory is an important source of information for the media, environmental organisations and other non-governmental organisations.

No external users have access to the statistics and analyses before they are published and accessible simultaneously for all users on https://www.ssb.no/en at 8 am. Prior to this, a minimum of three months' advance notice is given in the Statistics Release Calendar. This is one of Statistics Norway’s key principles for ensuring that all users are treated equally.

This statistic has one exception to this rule, that being the Norwegian Environment Agency having access for the areas in which they contribute to preparing the statistic. This is described in the principles for equal treatment of users at ssb.no.

The statistics are produced in a flexible model format which gives the opportunity to adjust to different national and international standards for emission data. Important international standards include IPCCs CRF classification for reporting to UNFCCC. At the same time, the statistics form a basis for analyses, both in Statistics Norway and other institutions.

The statistics are developed, produced and disseminated pursuant to Act no. 32 of 21 June 2019 relating to official statistics and Statistics Norway (the Statistics Act).

The statistics are part of the national program for official statistics 2021-2023, main area Nature, climate and environment, sub-area Climate and air pollution.

European Parliament and Council Regulation No. 691/2011 of 6 July 2011 on environmental financial accounts.

The emissions to air in Norway

The emissions to air in Norway have territorial delimitation - the statistics cover only activity on Norwegian territory regardless of the user's nationality. The scope of statistics is defined by emissions to air from human activity, shown by emission source and emission component.

The emissions to air from Norwegian economic activity

The emissions to air from Norwegian economic activity shows all emissions to air from industries in the Norwegian economy and Norwegian households, also abroad. Norwegian emissions abroad are included, while foreign consumption in Norway is excluded. This is called Norwegian economic territory and equals the delimitation of national accounts.

Preliminary figures have a lower degree of detail than the final figures.

The statistics include a number of different pollutants:

• Greenhouse gases: Carbon dioxide (CO2 ), nitrous oxide (N2O), methane (CH4 ), PFCs (perfluorocarbons), HFCs (hydrofluorocarbons) and sulphur hexafluoride (SF6 ).
• Accidification precursors: sulphur dioxide (SO2), nitrogen oxides (NOX), ammonia (NH3)
• Non-methane volatile organic compounds (NMVOC)
• Carbon monoxide (CO)
• Particulate matter (TSP, PM)
• Persistent organic pollutants (PAH, dioxines)
• Heavy metals: lead, cadmium, mercury, arsenic, chromium, copper

A detailed description of the data sources for the national air emission surveys is presented in the documentation reports National Inventory Report and Informative Inventory report. Link to the reports are found under Relevant documentation.

National emissions to air are mainly estimated from existing statistics on activity data and emission factors (emission per unit activity). Emissions from large industrial plants are based on data from the plants' own reports to the Norwegian Environment Agency.

No measurements or data collection take place in connection with the preparation of national emission statistics.

Statistics Norway collects data specifically for the emission inventory only to a small extent. The goal for data collection for the emissions inventory is that these statistics shall be based on already existing registers and statistics. However, it may be necessary to make some adjustments for this special purpose.

Data reported directly to the Norwegian Environment Agency (emission data from point sources, data from large industrial plants) are quality checked by the Norwegian Environment Agency. In addition, a consistency check is done by Statistics Norway. Statistics Norway is responsible for quality control of the activity data and emission figures from the model. Besides data from the energy balance, there are no particular controls performed on data from Statistics Norway's own statistics used in the emission calculations, as it is presupposed that the data already have been quality controlled.

The controls used in connection with the emission calculations can be divided into two parts:

1. Quality control and editing of input data, for example information about emissions per industrial plant from the Norwegian Environment Agency.

2. Quality control and editing of the emission figures (output from the model).

Editing is defined here as checking, examining and amending data.

1. Quality control and editing of input data:

The possibility to check the input data varies, depending on the collection methods and who collects the data. The controls will mainly be:

*To compare data with figures reported from the same unit earlier

*To collect missing data

*To contact industrial plants regarding obvious errors or by asking questions about the reported figures

Lack of data in the time series can be interpolated or filled in by use of estimates. The primary statistics in SSB are submitted to fixed quality control and editing routines. There is no additional quality control of primary data.

2. Quality control and editing of the emission figures (output from the model)

The national figures must be quality controlled source by source, by comparing with figures from previous years or figures for the same year calculated one year ago. Breaks in the series must be explained.

For comparisons between different calculations for the same year, the target is that all changes should be explained as change in data or method. For comparisons between different years, the target is to explain all large changes in the time series.

International examinations (reviews) of the emission inventory are performed annually by a group of experts nominated by IPCC .

The emission inventory is mainly based on calculations. Only a few industrial plants continuously measure their emissions. Some plants have periodic measurements that are scaled up to annual levels. For other plants and other sources than manufacturing industries, the emission figures are calculations, often of the type:

Emission = Activity data * emission factor

Activity data can be for example tonnes of fuel oil used by an industry, while the emission factor expresses the emission of a component in proportion to the activity (for example tonnes of SO 2 /tonne fuel oil). The emission factors are usually based on measured values, national or international.

The estimation methods are described in detail in National Inventory Report (NIR).

Not relevant

Employees of Statistics Norway have a duty of confidentiality.

Statistics Norway does not publish figures if there is a risk of the respondent’s contribution being identified. This means that, as a general rule, figures are not published if fewer than three units form the basis of a cell in a table or if the contribution of one or two respondents constitutes a very large part of the cell total.

Statistics Norway can make exceptions to the general rule if deemed necessary to meet the requirements of the EEA agreement, if the respondent is a public authority, if the respondent has consented to this, or when the information disclosed is openly accessible to the public.

More information can be found on Statistics Norway’s website under Methods in official statistics, in the ‘Confidentiality’ section.

To ensure confidentiality, the ‘perturbation’ method is used in these statistics.

One of the main goals for the emission inventories is to follow the development in the emissions over a given time period. To make this possible, recalculations are done for all years to obtain consistent time series when new factors or better methods are taken into account.

When new emission components are added, figures are added for the entire time series back to 1990. This is necessary because most new components are added according to international commitments, for which consistent time series are required.

International definitions, in addition to international guidelines for calculation and reporting of emission data, lead to comparable emission inventories in the different countries.

The emission figures are based on many different data sources. These sources may contain data from different registers or data reported from industrial plants. The model uses factors from various analyses. The results from the model will therefore reflect the uncertainties in the source material and the calculation methods that are used.

Sources of error and uncertainty connected to the different areas of statistics are described as a part of the documentation of sources for each statistic. Preliminary figures are based on more limited material than final figures and will therefore have higher uncertainty.

The statistics are based both on administrative sources, complete surveys and sample surveys. Calculation of sample variance, skewness or non-response for the emission figures is not relevant.

Uncertainties in the emission figures are calculated each year and documented as a part of Statistics Norway’s delivery to UNFCCC. These calculations are based on established methods which are documented in chapter 1 of the National Inventory Report (link under Relevant documentation) and in specific tables in Annex II, “Uncertainty”.

Uncertainty is calculated and reported both for the climate gas emissions last recording year and for the trend between 1990 and the last recording year.

The uncertainties are calculated for each climate gas (CO2, CH4, PFK, N2O, SF6 and F-gases) and for each emission source.

The calculation of uncertainty is based on the following principles (IPCC 2000):

Equation 1: The total emission figure x_total is the sum of n independent emissions figures / sources x₁,...x_n ; and x_total=x₁+x₂+...x_n. We describe the uncertainty U_i for the emission source i as two times coefficient of variation (CV) for x_i . This leads to U_i =2CV(x₁) =2σ_i/x_i · 100% where σ_i is standard deviation for x_i ; i =1,...n. This means that uncertainty for the total emission figure equals

Equation 2: In this case the total emission figure is x total is the product of n independent emissions figures / sources x₁,...x_n ; and x_total = x₁x₂...x_n. An estimate for the uncertainty for the total emission will be

An example of the equation 2 approach is the cacluation of combined uncertainty for activity data (AD) and emission factors (EF).

For both equation 1 and 2 an approximately 95 per cent confidence interval for the total emission figure be written as follows

On a national level the pollutants have been ranked according to uncertainty in National Inventory Report (NIR) as follows:

Greenhouse gases:

CO2 < CH4 < PFK < N2O < SF6 < HFK

The calculated uncertainty for the total greenhouse emissions for the latest year was 3 per cent. The trend between 1990 and the latest year also gave an uncertainty by 3 per cent. The uncertainty between the two latest years is not calculated but we assume that this uncertainty is lower than three per cent due to similar interannual conditions.

In addition to these calculations an annual uncertainty estimation is done based on the Monte Carlo method. The uncertainties in the greenhouse gas emission figures are documented in i.a. Flugsrud and Hoem (2011).

Revisions are planned changes to previously published statistics, for example publishing of final figures that replace preliminary statistics. See SSB’s principles for revision for more information (lenke)

The statistics for emissions to air are required to be comparable over time, as described in the UN’s reporting framework. As a result, the entire time series must be revised every year when final figures are published. If new information is available for previous years (for example new data sources, methods, or conversion factors), this will be implemented and published in revised time series.

The most recent version of figures for a given period will always be available in the statistics bank.

Revisions, also known as recalculations, are documented in National Inventory Report and Informative Inventory Report (link to the documents under Relevant documentation).