Global Greenhouse Gas Emissions Notes

Global Greenhouse Gas Emissions

  • Background

    • Increasing emissions of greenhouse gases from human activities have substantially increased atmospheric concentrations.
    • Climate change is a global issue, as every country emits greenhouse gases.
    • Emission levels vary by country, influenced by factors like economic activity, population, income, land use, and climate.
    • Tracking global emissions helps understand the roles of the U.S. and other nations in climate change.

  • 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 emission inventories.
    • Data and analysis are from the World Resources Institute’s Climate Analysis Indicators Tool (CAIT).
    • CAIT compiles data from internationally recognized greenhouse gas inventories.
    • Global carbon dioxide estimates are annual, while 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.
    • Gases are converted into carbon dioxide equivalents using 100-year global warming potentials (GWPs) for comparison.
    • Carbon dioxide has a GWP of 1.
    • This analysis uses GWPs from the IPCC's Second Assessment Report.
    • Methane has a GWP of 21, meaning a ton of methane warms 21 times more than a ton of carbon dioxide over 100 years.

Key Points

  • 2010 Global Emissions

    • Worldwide emissions reached nearly 46 billion metric tons of greenhouse gases (carbon dioxide equivalents).
    • This is a 35% increase from 1990.
    • Figures represent net emissions, including land use and forestry effects.

  • Emission Increases (1990-2010)

    • Global 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 the least at 9%.
    • Methane emissions increased by 15%.
    • Fluorinated gases emissions more than doubled.

  • Emission Sources

    • Energy production and use are the largest source (about 71% in 2010).
    • Agriculture accounts for 13% of emissions in 2010.
    • Land-use change and forestry are a net source of emissions globally due to deforestation, unlike in the U.S. where they act as a net sink.

  • Regional Emissions

    • Carbon dioxide emissions are increasing faster in some regions (e.g., Asia).
    • The majority of emissions come from Asia, Europe, and the United States, accounting for 88% of global emissions in 2012.

Figures

  • Figure 1: Global Greenhouse Gas Emissions by Gas, 1990–2010
    • Shows emissions of carbon dioxide, methane, nitrous oxide, and fluorinated gases.
    • Emissions are expressed in million metric tons of carbon dioxide equivalents.
    • Includes emissions and sinks due to land-use change and forestry.
    • HFCs are hydrofluorocarbons, PFCs are perfluorocarbons, and SF6 is sulfur hexafluoride.
  • Figure 2: Global Greenhouse Gas Emissions by Sector, 1990–2010
    • Shows worldwide emissions by sector.
    • Emissions are in million metric tons of carbon dioxide equivalents.
    • Includes emissions and sinks due to land-use change and forestry.
    • Sectors differ from U.S. emissions accounting.
    • International transport emissions (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
    • Shows carbon dioxide emissions by region.
    • Does not include emissions or sinks related to land-use change or forestry.
    • Inclusion of land-use change and forestry would affect apparent emissions from some regions.

Indicator Notes

  • Excludes gases not covered under the United Nations Framework Convention on Climate Change.
  • Excludes ozone-depleting substances (CFCs, HCFCs) phased out under the Montreal Protocol, even with high GWPs.
  • Excludes black carbon and aerosols.
  • Excludes emissions of greenhouse gases of natural origin.
  • 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 comprehensive data mainly for developed countries.
  • This indicator uses the CAIT database for a broader measure of global emissions.

Data Sources

  • Data 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 estimates are based on many of the same sources, such as those published by the Intergovernmental Panel on Climate Change (IPCC).