Global Greenhouse Gas Emissions Notes

Global Greenhouse Gas Emissions

Background
  • Increasing greenhouse gas emissions from human activities have substantially increased atmospheric concentrations of long-lived greenhouse gases.
  • Every country emits greenhouse gases, making climate change a global issue.
  • Emission levels vary by country based on economic activity, population, income, land use, and climate.
  • Tracking global emissions provides context for understanding the roles of the United States and other nations.
About the Indicator
  • Focuses on gases covered under the United Nations Framework Convention on Climate Change: carbon dioxide, methane, nitrous oxide, and fluorinated gases.
  • Participating countries are required to develop and submit emissions inventories.
  • Data is sourced from the World Resources Institute’s Climate Analysis Indicators Tool (CAIT), which compiles data from peer-reviewed inventories.
  • Global estimates for carbon dioxide are annual, but other gases are estimated every five years.
  • CAIT includes estimates of emissions and sinks from land use and forestry from the Food and Agriculture Organization of the United Nations.
  • Emissions are converted into carbon dioxide equivalents using 100-year global warming potentials.
  • Carbon dioxide has a global warming potential of 1.
  • Global warming potentials are based on the Intergovernmental Panel on Climate Change’s (IPCC’s) Second Assessment Report.
  • Methane has a global warming potential of 21, meaning a ton of methane warms 21 times more than a ton of carbon dioxide over 100 years.
Key Points
  • In 2010, worldwide emissions totaled nearly 46 billion metric tons of greenhouse gases (carbon dioxide equivalents), a 35% increase from 1990.
  • These numbers represent net emissions, including the effects of land use and forestry.
  • Between 1990 and 2010, emissions of all major greenhouse gases increased.
  • Carbon dioxide emissions increased by 42% and account for about three-fourths of total global emissions.
  • Nitrous oxide emissions increased by 9%, while methane increased by 15%.
  • Fluorinated gases emissions more than doubled.
  • Energy production and use are the largest emission source (71% in 2010), followed by agriculture (13% in 2010).
  • Land-use change and forestry are a net source of emissions globally due to deforestation, unlike in the United States where they are a net sink.
  • Carbon dioxide emissions are increasing faster in some regions (e.g., Asia) than others.
  • Asia, Europe, and the United States accounted for 88% of total global emissions in 2012.
Figure 1. Global Greenhouse Gas Emissions by Gas, 1990–2010
  • The figure shows worldwide emissions of carbon dioxide, methane, nitrous oxide, and fluorinated gases from 1990 to 2010 expressed in million metric tons of carbon dioxide equivalents.
  • Totals include emissions and sinks due to land-use change and forestry.
  • HFCs are hydrofluorocarbons, PFCs are perfluorocarbons, and SF6SF_6 is sulfur hexafluoride.
Figure 2. Global Greenhouse Gas Emissions by Sector, 1990–2010
  • The figure shows worldwide greenhouse gas emissions by sector from 1990 to 2010 expressed in million metric tons of carbon dioxide equivalents.
  • Totals include emissions and sinks due to land-use change and forestry.
  • The sectors differ from the economic sectors used in U.S. emissions accounting.
  • Emissions from international transport (aviation and marine) are separate from the energy sector.
  • The energy sector includes all other transportation activities.
Figure 3. Global Carbon Dioxide Emissions by Region, 1990–2012
  • The figure shows carbon dioxide emissions from 1990 to 2012 for different regions of the world.
  • Totals do not include emissions or sinks related to land-use change or forestry.
Indicator Notes
  • The indicator excludes gases that affect climate but are not covered under the United Nations Framework Convention on Climate Change.
  • Excludes ozone-depleting substances like chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) that are being phased out under the Montreal Protocol.
  • The indicator also excludes black carbon and aerosols.
  • Various emissions of greenhouse gases of natural origin are not covered.
  • Global emissions inventories for gases other than carbon dioxide are limited to five-year intervals.
  • The United Nations Framework Convention on Climate Change database has more comprehensive data mainly for developed countries that account for about half of global greenhouse gas emissions.
  • This indicator uses the broader CAIT database to provide a more representative measure of global greenhouse gas emissions.
Data Sources
  • Data is sourced from the World Resources Institute’s CAIT database.
  • CAIT compiles data from organizations including the International Energy Agency, EPA, the U.S. Carbon Dioxide Information Analysis Center, and the Food and Agriculture Organization of the United Nations.
  • Other global emissions estimates, such as those from the Intergovernmental Panel on Climate Change, are based on many of the same sources.