Emissions to air

CO₂ equivalents: The GWP value (Global Warming Potential) of a gas is defined as the cumulative impact on the greenhouse effect of 1 tonne of the gas compared with that of 1 tonne of CO₂ over a specified period of time. GWP values are used to convert emissions of greenhouse gases to CO₂ equivalents.

Substance and GWP value

Carbon dioxide (CO₂ ): 1

Methane (CH₄ ): 25

Nitrous oxide (N₂O): 298

Hydrofluorocarbons (HFCs):

HFC-23: 14 800

HFC-32: 675

HFC-125: 3 500

HFC-134: 1 100

HFC-134a: 1 430

HFC-143: 353

HFC-143a: 4 470

HFC-152a: 124

HFC-227ea: 3 220

Perfluorocarbons (PFCs):

CF₄ (PFC-14): 7 390

C₂ F₆ (PFC-116): 12 200

C₃ F₈ (PFC-218): 8 830

Sulphur hexafluoride (SF ₆ ): 22 800

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).

Published tables:

Emission by source

Emission by industry (NACE)

NAMEA (NACE according to Quarterly National Accounts)

Tables used in reports to UNFCCC

Name: Emissions to air
Topic: Nature and the environment

Division for Energy, Environmental and Transport Statistics

National figures

The figures are published annually in two versions; in June, preliminary figures for the previous year 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. The whole time series is recalculated annually as new information becomes available.

Annual reports to UNFCCC (United Nations Framework Convention on Climate Change)

Annual reports to Eurostat on emissions from Norwegian economic activity

Annual reports to CLRTAP (Gothenburg protocol)

Not relevant

The purpose of the statistics is to present the total emissions from Norwegian territory, distributed by sources, industries and energy goods. The statistics also show the achievement 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 was made in 1987. Since then, methodologies for estimating other emissions have been developed.

The statistics are to a great extent developed in order to cover the demands in the reporting to the protocols under the 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. For fishing and road traffic, all emissions originating from fuel sales in Norway are defined as Norwegian emissions.

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 emissions to air regularly is evaluated. 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 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.

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.

Not relevant (no data collection)

Not relevant

The statistics include emissions from Norwegian economic activity (specified under Background and purpose) and present emission surveys for 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

The emission figures are furthermore distributed between emission sources (e.g. manufacturing, road transport, agriculture) or by industry (e.g. metal production, construction).

A detailed description of the data sources for the national air emission surveys is presented in the National Inventory Report (NIR). National emissions to air are mainly estimated from existing statistics on activity level 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 does only to a small extent collect data specifically for the emission inventory. 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).

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 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 control of primary data.

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

The national figures must be 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.

Annually, there are international examinations (reviews) of the emission inventory, performed 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

The general rule for publication is that data cannot be released unless they contain information from at least three or more participants (i.e. industrial enterprises). This rule can be waived if permission from the parties involved is granted. Such data can be published if they are already made available for the public elsewhere.

One of the main goals for the emission inventories is to follow the development in the emissions over a 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.

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 explain 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 each year calculated and documented as a part of Statistics Norway’s deliverance to UNFCCC. These calculations are based on established methods which are documented in chapter 1 National Inventory Report (NIR) 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).

In December each year the emission statistics published in May is revised. Data back to 1990 is also revised if new information about emission factors, activity data or calculation methodology is available.