Feature Report: Calculating Greenhouse Gas Emissions

2 items of content in this feature report

Going in depth


National Inventories and Country Carbon Footprints

How are national and global greenhouse gas emissions calculated? It’s not so simple, because countries have widely divergent levels of development and differing statistical methods. In addition, they are highly interconnected due to the expansion of global trade, which makes it difficult to attribute emissions to each individual country.

Inventaires nationaux et empreintes carbone au niveau des pays
The burning of fossil fuels, particularly coal, is one of the main sources of CO2 emissions. Particulate matter, like here in the Bay of Bengal, is also a key source of pollution. ©NASA - EARTH OBSERVATORY

5.2 metric tons per year: France’s annual per-capita CO2 emissions generated within the national territory.

A Few Basic Definitions

greenhouse gas (ghg) Gas with physical properties that cause the Earth's atmosphere to warm up. There are a number of naturally occurring greenhouse gases...  – Greenhouse gases (GHGs) are gaseous compounds present in the atmosphere – either naturally or as a result of human activities – that absorb the infrared radiation emitted by the Earth’s surface and thereby contribute to its warming. The Kyoto ProtocolInternational agreement linked to the United Nations Framework Convention on Climate Change... identified six greenhouse gases: carbon dioxide (CO2See Carbon Dioxid ), nitrous oxide (N2O), methane (ch4)The main component of natural gas deposits and oil deposit gas caps. Methane is produced naturally by landfills... (CH4), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulfur hexafluoride (SF6). In 2013, the list was expanded to include nitrogen trifluoride (NF3), which emissions have spread due to the introduction of new electronic products. 

CO2 eq – To make it easier to compare GHG emissions, scientists devised a unit of measurement called carbon dioxide equivalent (CO2 eq), which assigns each gas a global warmingGlobal warming, also called planetary warming or climate change... potential (GWP) over a 100-year period. Because CO2 serves as the baseline for all calculations, it has a GWP of 1. Methane has a GWP of 23, which means that its heatIn the field of statistical thermodynamics today, heat refers to the transfer of the thermal agitation of the particles making up matter... trapping ability is 23 times greater than that of CO2. In 2013, 54 billion metric tons of CO2 equivalent (54 GtCO2 eq) were emitted into the world’s atmosphere1.

LULUCF – LULUCF stands for land use, land-use change and forestry. It primarily concerns changes in the world’s forest area and land use modifications. GHG emissions assessments may or may not include LULUCF considerations. People often refer to emissions “excluding LULUCF” – and limited to CO2 – in order to get a better picture of emissions directly related to fossil fuels and industrial activities.

In 2014, anthropogenic CO2 emissions (excluding LULUCF) totaled 35.7 billion metric tons1. Of this amount, nearly 42% were linked to the burning of coalCoal is ranked by its degree of transformation or maturity, increasing in carbon content from... , 31% to that of oil, 18% to that of natural gas and about 10% to industrial processes. The 2014 figure was a mere 0.5% higher than that of the previous year, compared to average annual emissions growth of 2.5% since 2000. Projections by the Global Carbon Project show that CO2 emissions continued to stabilize in 2015 and 20162. However, the results fall short of the objectives of the Paris AgreementOil contract under which the oil that is produced is shared between the state and the oil company... , which aims to limit the average global rise in temperature to 2°C maximum by the end of the century.

Relative Emissions According to Population and Wealth

Due to the international nature of climate action, emissions are often measured on a per‑country or per-region basis. A region is comprised of a group of countries that share certain basic features, such as the countries of Europe or North America, or the industrialized nations of the Organization for Economic Co-operation and Development (OECDFounded in 1960, the OECD promotes policies that will improve the economic and social well-being of people around the world... ).

Emissions can also be measured on a per-capita basis. This approach overturns some popular clichés: China, although the biggest polluter in absolute terms, produces only 7.6 metric tons of CO2 (excluding LULUCF) per year on a per-capita basis, compared to 16.5 metric tons for an American. In France, annual CO2 emissions per inhabitant total just over 5 metric tons.

Emissions can also be calculated on the basis of wealth, or relative to gross domestic product (GDP). This approach focuses on the “carbon intensity of GDP”, which is GHG emissions divided by GDP. Africa ranks at the top of the list, according to this metric, with a carbon intensity four times that of Europe, owing to its significantly lower GDP.

Carbon Footprint and Imported Emissions

The above calculations are based on national inventories that measure the amount of greenhouse gas emissions physically generated within a nation’s borders. The assessments are performed annually by the national authorities of each country (DGEC3 and CITEPA4 in France), according to standards defined by the United Nations Framework Convention on Climate Change (UNFCCC). It’s a territorial approach to calculating emissions.

To supplement the national inventories, a complementary approach, known as the carbon footprintThe carbon footprint (also known as greenhouse gas inventory) of a good or service measures the impact human activities have on the environment ... , was introduced. This method takes into account greenhouse gas emissions induced by final domestic demand. In other words, it comprises emissions embedded in imported goods and that are therefore emitted in another nation’s territory. These emissions are sometimes referred to as “the hidden emissions” of international trade. China is the most striking example. All countries consume Chinese products but, in the calculations, they aren’t responsible for the emissions generated by the production of these goods on Chinese soil. In the footprint approach, emissions from exported products are naturally subtracted from the national accounts. This is what is meant by the carbon footprint of final consumption. In France, emissions calculations are carried out by the SOeS5.

Based on the territorial approach, the GHG emissions of a Chinese inhabitant are roughly the same as those of a European (28-member EU). Using the footprint approach, the same Chinese person’s emissions are 30% lower than the European’s, and more than 50% below the OECD average (industrialized world). In France, the average per-capita carbon footprint (CO2 component) was estimated at 8.3 metric tons in 2015, compared to just over 5.2 metric tons according to the national inventory6.



Sources :

(1) See key figures – French Ministry of the Environment, Energy and the Sea (in french only) 

(2) See Global Carbon Atlas

(3) DGEC: Directorate General for Energy and Climate

(4) CITEPA: Interprofessional Technical Center for Studies on Air Pollution 

(5) SOeS : French Observation and Statistics Service (SOeS)

(6) See SOeS statistics (in french only)