Global Emissions by Source
Global greenhouse gas emissions can also be broken down by the economic activities that lead to their production.[1]
- Energy Supply (26% of 2004 global greenhouse gas emissions) – The burning of coal, natural gas, and oil for electricity and heat is the largest single source of global greenhouse gas emissions.
- Industry (19% of 2004 global greenhouse gas emissions) – Greenhouse gas emissions from industry primarily involve fossil fuels burned on-site at facilities for energy. This sector also includes emissions from chemical, metallurgical, and mineral transformation processes not associated with energy consumption. (Note: Emissions from electricity use are excluded and are instead covered in the Energy Supply sector.)
- Land Use, Land-Use Change, and Forestry (17% of 2004 global greenhouse gas emissions) – Greenhouse gas emissions from this sector primarily include carbon dioxide (CO2) emissions from deforestation, land clearing for agriculture, and fires or decay of peat soils. This estimate does not include the CO2 that ecosystems remove from the atmosphere. The amount of CO2 that is removed is subject to large uncertainty, although recent estimates indicate that on a global scale, ecosystems on land remove about twice as much CO2 as is lost by deforestation.[2]
- Agriculture (14% of 2004 GHG emissions) – global greenhouse gas emissions) – Greenhouse gas emissions from agriculture mostly come from the management of agricultural soils, livestock, rice production, and biomass burning.
- Transportation (13% of 2004 global greenhouse gas emissions) – Greenhouse gas emissions from this sector primarily involve fossil fuels burned for road, rail, air, and marine transportation. Almost all (95%) of the world’s transportation energy comes from petroleum-based fuels, largely gasoline and diesel.
- Commercial and Residential Buildings (8% of 2004 global greenhouse gas emissions) – Greenhouse gas emissions from this sector arise from on-site energy generation and burning fuels for heat in buildings or cooking in homes. (Note: Emissions from electricity use are excluded and are instead covered in the Energy Supply sector.)
- Waste and Wastewater (3% of 2004 global greenhouse gas emissions) – The largest source of greenhouse gas emissions in this sector is landfill methane (CH4), followed by wastewater methane (CH4) and nitrous oxide (N2O). Incineration of some waste products that were made with fossil fuels, such as plastics and synthetic textiles, also results in minor emissions of CO2.