Air Emissions Accounts

Carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) together account for the largest share of greenhouse gas (GHG) emissions across all OECD countries. However, their relative contributions vary significantly across different economic activities.

While most sectors—including manufacturing, electricity supply, construction, transport, various service industries, and households—emit predominantly carbon dioxide (CO₂), in agriculture, mining, and waste management, methane (CH₄) plays a more prominent role. Moreover, nitrous oxide (N₂O) emissions are concentrated in the agriculture and waste management sectors.

As the SEEA Central Framework uses the same classifications and accounting principles (e.g. residency of economic entities) as the System of National Accounts (SNA), air emissions as well as other SEEA measures, can be directly compared with GDP and other aggregates within the SNA. For example, emissions from transport services provided by resident carriers can be directly compared with the value added generated by the same sector. Such comparison supports the analysis of the decoupling between environmental pressures (i.e. air emissions) and economic output, or the calculation of emissions intensities per unit of GDP or value added. Moreover, this type of analysis can also be conducted at the industry level, as both frameworks use the same classifications.

The chart shows some evidence of possible absolute decoupling (i.e. the growth in the environmental pressure is flat or decreasing while economic activity is increasing) in the largest OECD economies as a whole. GDP exhibited consistent growth up until the COVID-19 outbreak, while air emissions initially declined, albeit modestly, increasing in 2018 to levels above those recorded in 2012, followed by a more marked decrease at the onset of the pandemic in 2020. Whereas GDP has resumed growth since 2021, GHG emissions remain below their pre-pandemic levels.