NOAA Global Monitoring Laboratory

NOAA Annual Greenhouse Gas Index

Global effective radiative forcing (W/m2, relative to 1750) from 22 long-lived greenhouse gases measured by NOAA, grouped as CO2, CH4, N2O, CFC* (CFCs plus CCl4, CH3CCl3 and halons, 8 gases; CFCs were 95% of the group's forcing in 2024), HCFCs (HCFC-22, -141b, -142b) and HFC* (seven HFCs plus SF6), with the CO2-equivalent mixing ratio (ppm) and the index itself (1990 = 1), annually from 1979. Also the global annual mean mole fractions used. Covers long-lived gases only: no aerosols, ozone or land-use forcing. Since the 2023 update all years use the IPCC AR6 effective radiative forcing expressions. The vintage is the page's "Updated" label.

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Numbers published from it

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Licence and credit

Licence: Public domain (work of the US federal government)
What the terms say: “The information on government servers are in the public domain, unless specifically annotated otherwise, and may be used freely by the public so long as you do not 1) claim it is your own (e.g. by claiming copyright for NOAA information – see next paragraph), 2) use it in a manner that implies an endorsement or affiliation with NOAA, or 3) modify it in content and then present it as official government material.”
From the producer's terms, checked 2026-10-04; re-checked automatically every week.
Credit we give: Data provided by NOAA Global Monitoring Laboratory, Boulder, Colorado, USA (https://gml.noaa.gov): The NOAA Annual Greenhouse Gas Index (AGGI), updated {version}. HFC-23 measurements: AGAGE (Prinn et al. 2018, doi:10.5194/essd-10-985-2018).
Notice: The NOAA Annual Greenhouse Gas Index values are US Government material from the NOAA Global Monitoring Laboratory and are not subject to copyright protection in the United States.
Copy of the raw file: Allowed: we keep a public copy of every version we use.
Cite as: Data/Image provided by NOAA Global Monitoring Laboratory, Boulder, Colorado, USA (https://gml.noaa.gov). Hofmann, D.J., J.H. Butler, E.J. Dlugokencky, J.W. Elkins, K. Masarie, S.A. Montzka, and P. Tans, (2006), The role of carbon dioxide in climate forcing from 1979–2004: Introduction of the Annual Greenhouse Gas Index, Tellus B, 58B, 614–619.

Files

Annual global effective radiative forcing by gas group (W/m2), total, CO2-equivalent (ppm), AGGI (1990 = 1) and annual change (% of 1990 forcing), from 1979. Header: Year,CO2,CH4,N2O,CFC*,HCFCs,HFCs*,Total,Total,1990 = 1,change *.
https://gml.noaa.gov/aggi/AGGI_Table.csv
Global annual mean dry-air mole fractions of the 22 gases used in the AGGI (CO2 ppm, CH4 and N2O ppb, halocarbons ppt), with "nd" for no data and trailing citation rows. The HFC-23 column is AGAGE data (Prinn et al. 2018).
https://gml.noaa.gov/aggi/NOAA_Annual_Mean_MoleFractions.csv

Status

Programme: The newest edition is the 2024 index, "Updated Fall 2025"; no 2025 index had been posted by 4 October 2026. The index is produced by GML, the lab the FY2026 and FY2027 US budget requests proposed closing; Congress rejected the FY2026 closure.
Updates: Annual (the 2024 index was posted in fall 2025)
Last check: Unchanged since the last fetch (2026-10-05T11:04:22Z)
Independent sources measuring the same thing: Indicators of Global Climate Change 2025