Global Greenhouse Gas Emissions Data
On This Page
Global Greenhouse Gas Emissions by Gas
Global Emissions by Gas
At the global scale, the key greenhouse gases emitted by human activities are:
- Carbon dioxide (CO2) - Fossil fuel use is the primary source of CO2. The way in which people use land is also an important source of CO2, especially when it involves deforestation. Land can also remove CO2 from the atmosphere through reforestation, improvement of soils, and other activities.
- Methane (CH4) - Agricultural activities, waste management, and energy use all contribute to CH4 emissions.
- Nitrous oxide (N2O) - Agricultural activities, such as fertilizer use, are the primary source of N2O emissions.
- Fluorinated gases (F-gases) - Industrial processes, refrigeration, and the use of a variety of consumer products contribute to emissions of F-gases, which include hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6).
Black carbon (BC) is a solid particle or aerosol, not a gas, but it also contributes to warming of the atmosphere. Learn more about BC and climate change on our Causes of Climate Change page.
Global Greenhouse Gas Emissions by Source
Global Emissions by Source
Global greenhouse gas emissions can also be broken down by the economic activities that lead to their production. 
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.
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.
Trends in Global Emissions
Global Carbon Dioxide (CO2) emissions from fossil-fuels 1990-2008
Global carbon emissions from fossil fuels have significantly increased since 1900. Emissions increased by over 16 times between 1900 and 2008 and by about 1.5 times between 1990 and 2008.
2008 Global CO2 Emissions from Fossil Fuel Combustion and some Industrial Processes (million metric tons of CO2)
Emissions by Country
In 2008, the top carbon dioxide (CO2) emitters were China, the United States, the European Union, India, the Russian Federation, Japan, and Canada. These data include CO2 emissions from fossil fuel combustion, as well as cement manufacturing and gas flaring. Together, these sources represent a large proportion of total global CO2 emissions.
Emissions and sinks related to changes in land use are not included in these estimates. However, changes in land use can be important - global estimates indicate that deforestation can account for 5 billion metric tons of CO2 emissions, or about 16% of emissions from fossil fuel sources. Tropical deforestation in Africa, Asia, and South America are thought to be the largest contributors to emissions from land-use change globally.  In areas such as the United States and Europe, changes in land use associated with human activities have the net effect of absorbing CO2, partially offsetting the emissions from deforestation in other regions.
Carbon Dioxide Information Analysis Center
National Inventory Submissions
World Development Indicators
World Resources Institute's Climate Analysis Indicators Tool (CAIT)
1. IPCC (2007). Climate Change 2007: Mitigation of Climate Change . Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
2. NRC (2010). Advancing the Science of Climate Change . National Research Council. The National Academies Press, Washington, DC, USA.
3. Houghton, R.A. (2008). Carbon Flux to the Atmosphere from Land-Use Changes: 1850-2005. In TRENDS: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A.
Note on emissions sector categories:
The global emission estimates described on this page are from the Intergovernmental Panel (IPCC) on Climate Change's Fourth Assessment Report. In this report, some of the sector categories are defined differently from how they are defined in the Sources of Greenhouse Gas Emissions page on this website. Transportation, Industry, Agriculture, and Land Use and Forestry are four global emission sectors that roughly correspond to the U.S. sectors. Energy Supply, Commercial and Residential Buildings, and Waste and Wastewater are categorized slightly differently. For example, the IPCC's Energy Supply sector for global emissions encompasses the burning of fossil fuel for heat and energy across all sectors. In contrast, the U.S. Sources discussion tracks emissions from the electric power separately and attributes on-site emissions for heat and power to their respective sectors (i.e., emissions from gas or oil burned in furnaces for heating buildings are assigned to the residential and commercial sector). The IPCC has defined Waste and Wastewater as a separate sector, while in the Sources of Greenhouse Gas Emissions page, waste and wastewater emissions are attributed to the Commercial and Residential sector.