---
- contact_email: ~
  contact_note: ~
  description: "Key Points:\r\n\r\n1. The Annual Greenhouse Gas Index (AGGI) is a measure of the capacity of Earth’s atmosphere to trap heat as a result of the presence of long-lived greenhouse gases. The AGGI provides standardized information about how human activity has affected the climate system through greenhouse gas emissions.\r\n\r\n2. This indicator demonstrates that the warming influence of greenhouse gases in the atmosphere has increased substantially over the last several decades. In 2013, the AGGI was 1.34, an increase of 34% since 1990.\r\n\r\n3. The AGGI can inform decisions about mitigation strategies. \r\n\r\nFull Summary:\r\n\r\nRadiative forcing (shown on the left vertical axis) is the change in the amount of solar radiation, or energy from the sun, that is trapped by the atmosphere and remains near Earth. When radiative forcing is greater than zero, it has a warming effect; when it is less than zero, it has a cooling effect. In this indicator, radiative forcing from long-lived greenhouse gases is shown relative to the year 1750. The AGGI (shown on the right vertical axis) is an index of radiative forcing normalized to the year 1990; it shows how the warming influence of greenhouse gases in the atmosphere has increased since that year. \r\n\r\nThis indicator demonstrates the change in radiative forcing resulting from changing concentrations of the following greenhouse gases: carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), chlorofluorocarbons (CFC-11 and CFC-12), and a set of 15 minor, long-lived halogenated gases. The National Oceanic and Atmospheric Administration (NOAA) Global Monitoring Division provides high-precision measurements of the abundance and distribution of long-lived greenhouse gases that are used to calculate global average concentrations. Radiative forcing for each gas is computed from these concentrations, and total radiative forcing for all gases is used to calculate the AGGI. \r\n\r\nThe AGGI shows that the warming influence of long-lived greenhouse gases in the atmosphere increased by 34% between 1990 and 2013. Carbon dioxide is currently the largest contributor to radiative forcing. Radiative forcing from methane increased between 2007 and 2013 after having been nearly constant from 1999 to 2006. Owing to the Montreal Protocol, an international agreement signed in 1987, CFCs have been decreasing since the mid- to late 1990s after a long period of increase. However, CFC replacements (many of the “other halogenated gases” in the graph) have been increasing since the phase-out of CFCs. \r\n\r\nFundamentally, the AGGI is a measure of what human activity has already done to affect the climate system through greenhouse gas emissions. It provides quantitative information in a simplified, standardized format that decision makers can use to inform mitigation strategies.\r\n"
  display_name: 'Indicator: Annual Greenhouse Gas Index '
  doi: ~
  frequency: ~
  identifier: indicator-annual-greenhouse-gas-index
  in_library: ~
  publication_year: 2015
  report_type_identifier: indicator
  summary: "Key Points:\r\n\r\n1. The Annual Greenhouse Gas Index (AGGI) is a measure of the capacity of Earth’s atmosphere to trap heat as a result of the presence of long-lived greenhouse gases. The AGGI provides standardized information about how human activity has affected the climate system through greenhouse gas emissions.\r\n\r\n2. This indicator demonstrates that the warming influence of greenhouse gases in the atmosphere has increased substantially over the last several decades. In 2013, the AGGI was 1.34, an increase of 34% since 1990.\r\n\r\n3. The AGGI can inform decisions about mitigation strategies. \r\n\r\nFull Summary:\r\n\r\nRadiative forcing (shown on the left vertical axis) is the change in the amount of solar radiation, or energy from the sun, that is trapped by the atmosphere and remains near Earth. When radiative forcing is greater than zero, it has a warming effect; when it is less than zero, it has a cooling effect. In this indicator, radiative forcing from long-lived greenhouse gases is shown relative to the year 1750. The AGGI (shown on the right vertical axis) is an index of radiative forcing normalized to the year 1990; it shows how the warming influence of greenhouse gases in the atmosphere has increased since that year. \r\n\r\nThis indicator demonstrates the change in radiative forcing resulting from changing concentrations of the following greenhouse gases: carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), chlorofluorocarbons (CFC-11 and CFC-12), and a set of 15 minor, long-lived halogenated gases. The National Oceanic and Atmospheric Administration (NOAA) Global Monitoring Division provides high-precision measurements of the abundance and distribution of long-lived greenhouse gases that are used to calculate global average concentrations. Radiative forcing for each gas is computed from these concentrations, and total radiative forcing for all gases is used to calculate the AGGI. \r\n\r\nThe AGGI shows that the warming influence of long-lived greenhouse gases in the atmosphere increased by 34% between 1990 and 2013. Carbon dioxide is currently the largest contributor to radiative forcing. Radiative forcing from methane increased between 2007 and 2013 after having been nearly constant from 1999 to 2006. Owing to the Montreal Protocol, an international agreement signed in 1987, CFCs have been decreasing since the mid- to late 1990s after a long period of increase. However, CFC replacements (many of the “other halogenated gases” in the graph) have been increasing since the phase-out of CFCs. \r\n\r\nFundamentally, the AGGI is a measure of what human activity has already done to affect the climate system through greenhouse gas emissions. It provides quantitative information in a simplified, standardized format that decision makers can use to inform mitigation strategies.\r\n"
  title: 'Indicator: Annual Greenhouse Gas Index '
  topic: ~
  type: report
  uri: /report/indicator-annual-greenhouse-gas-index
  url: http://www.globalchange.gov/browse/indicators/indicator-annual-greenhouse-gas-index
- contact_email: ~
  contact_note: ~
  description: "Key Points:\r\n\r\n1.\tThis indicator tracks the global monthly average concentration of carbon dioxide in the atmosphere, capturing both seasonal and interannual trends. Carbon dioxide concentration is an important measure of how human activity has increased the heat-trapping capacity of the atmosphere.\r\n\r\n2.\tGlobal monthly average concentrations of carbon dioxide have risen steadily from 339 parts per million in 1980 (averaged over the year) to 395 parts per million in 2013, an increase of about 16% in just over 30 years.\r\n\r\n3.\tThis indicator can inform carbon emissions policies at national and international levels.\r\n \r\nFull Summary:\r\n\r\nGreenhouse gases such as carbon dioxide trap heat in the atmosphere. Increasing concentrations of these gases have driven an increase in global temperatures. The Annual Greenhouse Gas Index (AGGI) shows that over the past decade, increases in carbon dioxide are responsible for about 84% of the increase in the heat-trapping capacity of the atmosphere. Although the atmospheric concentration of carbon dioxide fluctuates over seasonal cycles, as illustrated by the saw-tooth pattern in the graph, the overall trend has been a steady increase since data collection began. Global monthly average concentrations of carbon dioxide have risen from around 339 parts per million in 1980 (averaged over the year) to 395 parts per million in 2013, an increase of about 16%. \r\n\t\r\nThe National Oceanic and Atmospheric Administration (NOAA) Global Monitoring Division has measured carbon dioxide and other greenhouse gases for several decades through a globally distributed network of about 70 air sampling sites, including the Mauna Loa Observatory in Hawai’i. The data for this indicator come from a subset of about 40 of these sites located in isolated regions of the ocean.  \r\n\r\nInformation about global carbon dioxide concentrations can inform emissions policies at national and international levels. \r\n"
  display_name: 'Indicator: Atmospheric Carbon Dioxide'
  doi: ~
  frequency: ~
  identifier: indicator-atmospheric-carbon-dioxide
  in_library: ~
  publication_year: 2015
  report_type_identifier: indicator
  summary: "Key Points:\r\n\r\n1.\tThis indicator tracks the global monthly average concentration of carbon dioxide in the atmosphere, capturing both seasonal and interannual trends. Carbon dioxide concentration is an important measure of how human activity has increased the heat-trapping capacity of the atmosphere.\r\n\r\n2.\tGlobal monthly average concentrations of carbon dioxide have risen steadily from 339 parts per million in 1980 (averaged over the year) to 395 parts per million in 2013, an increase of about 16% in just over 30 years.\r\n\r\n3.\tThis indicator can inform carbon emissions policies at national and international levels.\r\n \r\nFull Summary:\r\n\r\nGreenhouse gases such as carbon dioxide trap heat in the atmosphere. Increasing concentrations of these gases have driven an increase in global temperatures. The Annual Greenhouse Gas Index (AGGI) shows that over the past decade, increases in carbon dioxide are responsible for about 84% of the increase in the heat-trapping capacity of the atmosphere. Although the atmospheric concentration of carbon dioxide fluctuates over seasonal cycles, as illustrated by the saw-tooth pattern in the graph, the overall trend has been a steady increase since data collection began. Global monthly average concentrations of carbon dioxide have risen from around 339 parts per million in 1980 (averaged over the year) to 395 parts per million in 2013, an increase of about 16%. \r\n\t\r\nThe National Oceanic and Atmospheric Administration (NOAA) Global Monitoring Division has measured carbon dioxide and other greenhouse gases for several decades through a globally distributed network of about 70 air sampling sites, including the Mauna Loa Observatory in Hawai’i. The data for this indicator come from a subset of about 40 of these sites located in isolated regions of the ocean.  \r\n\r\nInformation about global carbon dioxide concentrations can inform emissions policies at national and international levels. \r\n"
  title: 'Indicator: Atmospheric Carbon Dioxide'
  topic: ~
  type: report
  uri: /report/indicator-atmospheric-carbon-dioxide
  url: http://www.globalchange.gov/browse/indicators/indicator-atmospheric-carbon-dioxide