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Page History: 7.2 CO2 emissions, total, per capita and per $1 GDP (PPP)

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Page Revision: 2012/11/05 11:36



Goal 7. Ensure environmental sustainability Target 7.A. Integrate the principles of sustainable development into country policies and programmes and reverse the loss of environmental resources


This indicator is defined as the total carbon dioxide (CO2) emissions from energy, industrial processes, agriculture and waste (minus CO2 removal by sinks), presented as total emissions, emissions per unit population of a country, and emissions per unit value of a country’s gross domestic product (GDP) , expressed in terms of purchasing power parity (PPP).

Total carbon dioxide (CO2) emissions are defined as the total amount of carbon dioxide emitted by a country as a consequence of human activities, minus carbon dioxide removals by sinks. The term “total” implies that emissions from all national activities are considered. The typical sectors for which CO2 emissions are estimated are energy, industrial processes, agriculture and waste. Emissions resulting from land-use changes and forest cover changes are also calculated. The energy sector includes emissions from the consumption of solid, liquid and gaseous fuels and emissions from oil/gas flaring. Industrial processes include emissions from cement production and some other processes. The waste sector includes emissions from waste incineration.

Sinks are processes, activities or mechanisms which remove a greenhouse gas, an aerosol or a precursor of a greenhouse gas from the atmosphere. Forests and other vegetation are considered sinks because they remove carbon dioxide through photosynthesis.

Gross domestic product (GDP) is an aggregate measure of production equal to the sum of the gross values added of all resident institutional units engaged in production (plus any taxes, and minus any subsidies, on products not included in the value of their outputs). It is calculated without making deductions for the consumption of fixed capital or for depletion and degradation of natural resources.

The purchasing power parity (PPP) conversion factor is the number of units of a country's currency required to buy the same amounts of goods and services in the domestic market as the United States dollar would buy in the United States. Using the PPP factor is often considered as a practical way to address the problem of possible imperfection in the currency exchange rates observed on the real currency markets.

Method of computation
This indicator is calculated by first computing total carbon dioxide emissions. The Intergovernmental Panel on Climate Change (IPCC) has developed methodologies for estimating carbon dioxide emissions which are classified into three tiers—the higher the tier, the higher the quality and accuracy of the data estimate. Tier 1 methods are relatively straightforward and require little country-specific data whereas Tier 3 methodologies are complex and usually require a large amount of country-specific data. The application of these methodologies by countries varies according to specific national circumstances.

Emissions are normally estimated at the level of individual emissions sources, which may correspond to a physical facility (e.g. a power plant) or to an industrial or economic group (e.g. cement production). For each individual source category, CO2 emissions are often estimated using an equation of the type shown below (which corresponds to a Tier 1 method):

where Emissionsfuel are CO2 emissions by type of fuel (for the given category), Fuel Combustedfuel is the quantity of fuel combusted, and Emission Factorfuel,tech. is the CO2 emission factor by type of fuel, which may depend on the combustion technology used. Sometimes a carbon oxidation factor (often assumed to equal 1) is added to this equation. While the equation is simple, estimating values for the amount of fuel combusted and selecting emission factors which are consistent with the definitions of the IPCC emission categories are more difficult.

The formula above does not apply to estimating CO2 emissions from industrial processes where the emissions need to be calculated for each process depending on the chemical reactions involved.

Carbon dioxide emissions can be expressed as units of carbon dioxide or converted to units of carbon content. To convert carbon dioxide to carbon content, the quantity of carbon dioxide is multiplied by the ratio of the molecular weight of carbon to that of carbon dioxide (12/44).

Once total CO2 emissions are estimated, the indicator is calculated by dividing total carbon dioxide emissions by total population, and by dividing total carbon dioxide emissions by GDP in terms of PPP


The indicator monitors countries’ efforts to reduce CO2 emissions. CO2 emissions are largely a by-product of energy production and use. They account for the largest share of greenhouse gases associated with global warming. The major part of CO2 is released as a result of combustion processes when fossil fuels such as coal, oil and gas are burned, usually in order to produce energy. CO2 is also released as part of certain industrial processes, for example in cement production, and in the waste incineration process.

Continued growth of greenhouse gas emissions at or above the current rates can cause further warming and induce many changes in the global climate system. As CO2 is the major component of greenhouse gases, monitoring CO2 emissions is particularly important. Rising CO2 emissions lead to increases in the concentration of carbon dioxide in the atmosphere, higher global temperatures, rising sea levels and other sizable adverse impacts on the animals, plants and people inhabiting the planet. Several international conventions and agreements aim to halt and reverse the effects of emissions, the United Nations Framework Convention on Climate Change (UNFCCC) and its Kyoto Protocol being the most prominent.


National carbon emissions are estimated from detailed data on emission sources, using source-specific emission factors. Emission inventories are usually compiled by energy or environment ministries, or by specialized environmental agencies.


Generally, CO2 emissions are calculated for individual sources or source categories which are then aggregated to obtain a national total. The number of individual source categories may vary depending on data availability, the organizational and methodological framework of the assessment, and the resources available. The list below illustrates a typical disaggregation of CO2 emissions by category that is used by countries that report CO2 emissions to the UNFCCC. Many countries use even more detailed disaggregations of their CO2 sources.

  1. Energy
    1. Fuel Combustion
      1. Energy Industries
      2. Manufacturing Industries and Construction
      3. Transport
      4. Other Sectors
      5. Other
    2. Fugitive Emissions from Fuels
      1. Solid Fuels
      2. Oil and Natural Gas

  2. Industrial Processes
    1. Mineral Products
    2. Chemical Industry
    3. Metal Production
    4. Other Production
    5. Production of Halocarbons and SF6
    6. Consumption of Halocarbons and SF6
    7. Other
  3. Solvent and Other Produce Use
  4. Agriculture
    1. Enteric Fermentation
    2. Manure Management
    3. Rice Cultivation
    4. Agricultural Soils
    5. Prescribed Burning of Savannas
    6. Field Burning of Agricultural Residues
    7. Other
  5. Land Use, Land-Use Change and Forestry
    1. Forest Land
    2. Cropland
    3. Grassland
    4. Wetlands
    5. Settlements
    6. Other Land
    7. Other
  6. Waster
    1. Solid Waste Disposal on Land
    2. Waste-water Handling
    3. Waste Incineration
    4. Other
  7. Other

Since disaggregated emissions are usually available, CO2 emissions indicators can be calculated at various levels, from national totals to emissions from specific industries. However, the more the indicator is disaggregated, the less transparent its interpretation becomes.


Carbon dioxide is only one of the greenhouse gases and therefore this indicator provides information on only one part of overall greenhouse gas emissions. Accordingly, the overall impact on climate change may be underestimated if only CO2 emissions are included in the estimate. However, usually the share of CO2 in total greenhouse gas emissions is high, ranging from 70 per cent to 90 per cent, and it is therefore reasonable to use CO2 emissions as a simple proxy for a more complex composition of greenhouse gases.

CO2 emissions/removals from land-use change and forestry are often known with much less certainty than emissions from other sectors, if they are known at all. In uncertain cases, CO2 emissions/removals from forests and land-use changes can be excluded and “total” CO2 emissions can be estimated as the sum of emissions from energy, industrial processes and waste.


Not applicable for this indicator


Data at the global and regional level are calculated by the United Nations Statistics Division (UNSD) on the basis of country-level data provided by the UNFCCC Secretariat (for most industrialized countries) and the Carbon Dioxide Information Analysis Center (CDIAC) of the US Department of Energy (DOE) (for all other countries). The two sets of data are calculated with a rather different approach.

The UNFCCC Secretariat compiles CO2 emissions data submitted by UNFCCC Annex I Parties. These data are often prepared using disaggregations of emissions/removals by source/sink categories based on the more complex methodologies recommended by the IPCC (Tier 2 and Tier 3 methods). The data are prepared and reported annually with a two-year lag. The entire data series is normally provided because data for earlier years are recalculated every year to ensure consistency of the time series.

CDIAC estimates CO2 emissions for all other countries for which the UNFCCC Secretariat does not provide data. These emissions estimates are derived primarily from energy statistics published by UNSD, using mostly IPCC Tier 1 methods. Energy statistics are compiled primarily from annual questionnaires distributed by UNSD and supplemented by official national statistical publications and, in a few cases, by other sources and estimates. These estimates are made annually, with a two-year lag.

Since both sets of data use methodologies recommended by the IPCC or consistent with IPCC recommendations, no significant data inconsistencies are expected between the two sets, although, for a given country, results of an emission estimate may differ.

Due to a lack of data relating to emissions from land use, land-use change and forestry, the CO2 emissions estimates used in the MDG process are made without accounting for CO2 emissions/removals from forests and land-use changes.




CARBON DIOXIDE INFORMATION ANALYSIS CENTRE. Fossil Fuel CO2 Emissions. Oak Ridge, Tennessee. Internet site http://cdiac.ornl.gov/trends/emis/meth_reg.html.

INTER-GOVERNMENTAL PANEL ON CLIMATE CHANGE (2006). 2006 IPCC Guidelines for National Greenhouse Gas Inventories. Geneva. Available from http://www.ipcc-nggip.iges.or.jp/public/2006gl/index.html.

INTER-GOVERNMENTAL PANEL ON CLIMATE CHANGE (2003). Good Practice Guidance for Land Use, Land-Use Change and Forestry. Geneva. Available from http://www.ipcc-nggip.iges.or.jp/public/gpglulucf/gpglulucf.htm.

INTER-GOVERNMENTAL PANEL ON CLIMATE CHANGE (2000). Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories. Geneva. Available from http://www.ipcc-nggip.iges.or.jp/public/gp/english.

INTER-GOVERNMENTAL PANEL ON CLIMATE CHANGE (1996). Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories. Geneva. Available from http://www.ipcc-nggip.iges.or.jp/public/gl/invs1.htm.

MARLAND, G., and R.M. ROTTY (1984). Carbon dioxide emissions from fossil fuels: a procedure for estimation and results for 1950–1982. Tellus. 36(B): 232–61.

UNITED NATIONS (1996). Glossary of Environmental Statistics. New York. Available from http://unstats.un.org/unsd/publication/SeriesF/SeriesF_67E.pdf.

UNITED NATIONS FRAMEWORK CONVENTION ON CLIMATE CHANGE (annual). National Greenhouse Gas Inventory Submissions by Annex I Parties. Geneva. Internet site http://unfccc.int/national_reports/annex_i_ghg_inventories/national_inventories_submissions/items/4771.php.

UNITED NATIONS FRAMEWORK CONVENTION ON CLIMATE CHANGE. Greenhouse Gas Data Interface. Internet site http://ghg.unfccc.int.

UNITED NATIONS STATISTICS DIVISION (annual). Energy Statistics Yearbook. New York. Available from http://unstats.un.org/unsd/energy/yearbook/default.htm.

WORLD METEOROLOGICAL ORGANIZATION and UNITED NATIONS ENVIRONMENT PROGRAMME. Intergovernmental Panel on Climate Change. Geneva. Internet site http://www.ipcc.ch.

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