e-Digest Statistics about: Climate Change
How UK Emissions of Greenhouse Gases are measured
This page is for reference to past methodology. A revision will be posted as soon as possible. [31 January 2008]
UK greenhouse gas emission estimates are updated annually as part of the National Atmospheric Emissions Inventory. The inventory methodology is described in more detail in the Air Quality topic.
Emission estimates are calculated by applying emission factors to statistical information on processes producing emissions, usually fuel consumption, as opposed to measurements at the point of emission. Fossil fuel combustion is the major source of UK CO2 emissions and so fuel consumption statistics, combined with appropriate emission factors for each source and type of fuel, are used to estimate the majority of CO2 emissions. Emission factors in this case reflect the carbon contents of fuels.
For estimates of emissions by end user, a simple pro rata method is used to re-allocate estimated emissions from power stations and other fuel processing industries to final users of delivered energy. This method, for example, does not take into account higher emissions from increased coal and oil-fired generation used to meet peak domestic demand for electricity. Emissions by end user are therefore subject to more uncertainty than those by source and should only be used to give a broad indication by sector.
Greenhouse Gas Emissions on an IPCC basis
The tables show total UK emissions of greenhouse gases calculated in the format required by IPCC [7]. The IPCC format is used for reporting UK greenhouse gas emissions to the Framework Convention on Climate Change. A UK report is published and submitted to the Convention annually [8]. Emission estimates on the IPCC basis are available back to 1990. The figures for 1970-1989 included in Tables are on a slightly different basis as footnoted in the tables.
Emissions from the 'Land Use Change and Forestry' (LUCF) category shown are reported as a net figure, that is emissions from sources minus removals from sinks, following IPCC good practice guidance [28].
In previous years detailed figures for individual greenhouse gases were presented on a UNECE basis, which differs slightly from the IPCC format in terms of the coverage of land use change and soil emissions, but all the greenhouse gas tables are now shown in the same IPCC format. The emissions of atmospheric pollutants shown in the Air Quality topic of the e-Digest are calculated on the UNECE basis.
Emissions in environmental accounts
Information about emissions by economic sector, on a consistent basis with the economic data held in the National Accounts, is published each year in the UK National Accounts Blue Book and can be found on the UK environmental accounts website. The estimates are based upon the NAEI but use other sources of information to allocate emissions from sources such as road transport to the sector which owns the transport. The estimates also follow as far as possible National Accounts conventions on the scope of the emissions included - this means that emissions from the international operations of UK airline, shipping and other transport operators are included, whereas they are excluded under IPCC and UNECE conventions. Adjustments are also made for emissions from energy either purchased or used overseas by UK residents.
International greenhouse gas emissions data
The European Environment Agency compiles greenhouse gas inventory data for the EU from the individual inventories of member states, and produces various publications, including the EU's annual greenhouse gas inventory submission to the UNFCCC secretariat. The UNFCCC web site provides a wide range of information including official documents, national submissions and an international database of emissions data.
Accuracy of emissions estimates
There are uncertainties associated with all estimates of greenhouse gas emissions. However, although for any given year considerable uncertainties may surround the emission estimates for a pollutant, it is important to note that trends over time are likely to be much more reliable. To estimate accuracy, an uncertainty distribution is allocated to each emission factor and activity rate. The parameters of the distributions are set by analysing the available data on emission factors and activity data or by expert judgement. The estimated uncertainties relating to the 2003 figures and the trends since 1990 are given in table 15.
For more information on uncertainties see 'Treatment of Uncertainties for National Estimates of Greenhouse Gas Emissions' [11] or the annual inventory reports on the NAEI website.
Data Tables:
| Table
No. |
Title | Download
file type |
| 15 | Uncertainty in estimates and Global Warming Potential (GWP) of UK Greenhouse Gas emissions |
- References, further reading and links to other resources:
- [7] IPCC, (1995). IPCC Guidelines for National Greenhouse Inventories.
- [8] Baggott SL, Brown L, Cardenas L, Downes MK, Garnett E, Hobson M, Jackson J, Milne R, Mobbs, DC, Passant N, Thistlethwaite G, Thomson A, Watterson JD (2006). UK Greenhouse Gas Inventory 1990 to 2004: Annual Report for submission under the Framework Convention on Climate Change. AEA Technology
- [11] Salway AG, (2002) Treatment of Uncertainties for National Estimates of Greenhouse Gas Emissions. AEA Technology
- [28] IPCC (2003) Good Practice Guidance for Land Use, Land-Use Change and Forestry
- Internet Links:
- Defra Climate Change policy pages
- Defra papers published to accompany the 2003 Energy White Paper
- Intergovernmental Panel on Climate Change
- National Atmospheric Emissions Inventory
- European Environment Agency
- United Nations Framework Convention on Climate Change
- National Statistics, UK environmental accounts 'Blue Book'
Further Information:
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Page last modified: 7 August 2006
Page published: 7 August 2006