Global Greenhouse Gas Emissions Notes

Increasing greenhouse gas emissions from human activities have led to substantial increases in atmospheric concentrations.
Climate change is a global issue, with every country contributing emissions.
Emission levels vary by country due to factors like economic activity, population, income, land use, and climate.
Tracking global emissions provides context for understanding the roles of individual nations.

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 inventory these emissions.
Data is sourced from the World Resources Institute’s Climate Analysis Indicators Tool (CAIT), which compiles data from EPA and other government agencies.
Global carbon dioxide estimates are published annually, while other gases' estimates are available every five years.
CAIT includes estimates of emissions and sinks from land use and forestry, based on data from the Food and Agriculture Organization of the United Nations.
To compare different gases, 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 emissions contributes 21 times as much warming as a ton of carbon dioxide emissions over 100 years.

In 2010, worldwide emissions totaled nearly 46 billion metric tons of greenhouse gases (carbon dioxide equivalents), a 35% increase from 1990.
These figures represent net emissions, including land use and forestry effects.
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 sink in the U.S. but a net source globally due to deforestation.
Carbon dioxide emissions are increasing faster in Asia compared to other regions.
Asia, Europe, and the United States accounted for 88% of total global emissions in 2012.

Shows worldwide emissions of carbon dioxide, methane, nitrous oxide, and fluorinated gases from 1990 to 2010.
Emissions are expressed in million metric tons of carbon dioxide equivalents.
Totals include emissions and sinks from land-use change and forestry.
HFCs are hydrofluorocarbons, PFCs are perfluorocarbons, and SF6 is sulfur hexafluoride.
Data sources: WRI, 2014; FAO, 2014

Shows worldwide greenhouse gas emissions by sector from 1990 to 2010.
Emissions are expressed in million metric tons of carbon dioxide equivalents.
Totals include emissions and sinks from land-use change and forestry.
Sectors differ from 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.
Data sources: WRI, 2014; FAO, 2014

Shows carbon dioxide emissions from 1990 to 2012 for different regions.
Totals do not include emissions or sinks related to land-use change or forestry.
Inclusion of land-use change and forestry would increase/decrease emissions for some regions.
Data source: WRI, 2015

The indicator excludes gases not covered under the United Nations Framework Convention on Climate Change.
Excludes ozone-depleting substances like CFCs and HCFCs being phased out under the Montreal Protocol.
Also excludes black carbon and aerosols.
Excludes various 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 more comprehensive data for mostly developed countries, accounting for about half of global greenhouse gas emissions.
The indicator uses the broader CAIT database for a more representative measure.

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 emissions estimates are based on many of the same sources, such as the estimates published by the Intergovernmental Panel on Climate Change.