Global Emissions by Gas

At the global scale, the key greenhouse gases emitted by human activities are:

Global GHG emissions by gas: 65% is from carbon dioxide fossil fuel use and industrial processes. 11% is from carbon dioxide deforestation, decay of biomass, etc. 16% is from methane. 6% is from nitrous oxide and 2% is from fluorinated gases.Source: IPCC (2014) EXIT based on global emissions from 2010. Details about the sources included in these estimates can be found in the Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate ChangeEXIT
  • 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. CO2 can also be emitted from direct human-induced impacts on forestry and other land use, such as through deforestation, land clearing for agriculture, and degradation of soils. Likewise, land can also remove CO2 from the atmosphere through reforestation, improvement of soils, and other activities.
  • Methane (CH4): Agricultural activities, waste management, energy use, and biomass burning all contribute to CH4 emissions.
  • Nitrous oxide (N2O): Agricultural activities, such as fertilizer use, are the primary source of N2O emissions. Biomass burning also generates N2O.
  • 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 is a solid particle or aerosol, not a gas, but it also contributes to warming of the atmosphere. Learn more about black carbon and climate change on our Causes of Climate Change