Global overview of GHG emissions

Breakdown of total GHG emissions (excluding LULUCF*) in 2021

* See glossary.
Note: distribution calculated according to the GWP of each gas over 100 years. CO₂ = carbon dioxide; N₂O = nitrous oxide ; CH₄ = methane.
Source: SDES, based on EDGAR, 2022

The Global Warming Potential (GWP) is used to calculate, in t CO₂ eq, the impact of the emissions of each gas on the greenhouse effect (see glossary). The GWP of a gas depends on the period over which it is calculated (see p. 20). For example, the GWP of methane is 28 to 30 when calculated over 100 years, and 84 when calculated over 20 years. With the 100-year GWP (the most commonly used), CO₂ accounts for three-quarters of GHG emissions in 2021.

In 2021, global greenhouse gas emissions (excluding LULUCF) amount to 52.6 Gt CO₂ eq. They have more than doubled since 1970, and increased by 58% between 1990 and 2021. The LULUCF sector makes a positive contribution to global GHG emissions. In 2020, emissions from this sector were estimated at 5.8 Gt CO₂ eq.

Worldwide GHG emissions by fuel

Note: the emissions included here are those linked to fossil fuel combustion and fugitive emissions (see glossary). They account for 70% of GHG emissions.

Source: IEA, 2023

In 2021, economic activity picked up after the slowdown caused by the pandemic. GHG emissions from energy combustion followed suit, rising by 5.5% to almost the same level as in 2019. This increase concerns all fuels: +6% for coal,+5.5% for oil,+4.8% for natural gas and +1.2% for other fuels.

Coal combustion generates 43% of global emissions (up 7 points on 1971), compared with 33% for oil (down 17 points) and 23% for natural gas (up 9 points).

In 50 years, global GHG emissions linked to energy combustion have multiplied by 2.3.

Primary energy mix in the world

Source: IEA, 2023

Energy-related emissions depend on the level of energy consumption (up 168% between 1971 and 2021) and on the primary energy mix (see glossary), which at global level remains dominated by fossil fuels in 2021 (oil, coal and natural gas: 80% of the total between them). Oil remains the world's leading energy source, even though its share fell by 15 points between 1971 and 2021, mainly to the benefit of natural gas (+7 points) and nuclear power (+4 points). However, coal remains the leading source of emissions. Indeed, it has a much higher emission factor than natural gas and oil (see p. 84). Coal consumption, which had risen sharply in the 2000s, has stagnated or even declined in recent years. Although stable overall since 1971, the share of renewable energies has risen slightly over the last ten years, reaching 15% of the mix in 2021.

Sectoral breakdown of GHG emissions from energy combustion in 2021

* Including cogeneration and autoproduction.
Source: IEA, 2023

In 2021, electricity generation remains the world's largest GHG-emitting sector, accounting for 39% of total emissions from energy combustion. It is followed by transport (21%) and industry (17%, including construction). In China, industry and the energy sector (electricity and non-electricity) together account for 81% of GHG emissions from energy combustion, compared with a world average of 61%. Transportation plays a greater role in the United States (34%) and the European Union (29%), as do the residential and services sectors. Worldwide, fugitive emissions (see glossary) account for 9% of emissions linked to energy combustion.