NOAA Global Monitoring Laboratory

Trends in globally-averaged methane, nitrous oxide and sulphur hexafluoride

Monthly and annual means of methane (from 1983), nitrous oxide (from 2001) and sulphur hexafluoride averaged over NOAA's global network of marine surface air-sampling sites, with uncertainties from a network bootstrap and a measurement Monte Carlo taken in quadrature, and annual increases from 1 January to 1 January.

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Numbers published from it

Licence and credit

Licence: Public domain (work of the US federal government)
What the terms say: “These data are made freely available to the public and the scientific community in the belief that their wide dissemination will lead to greater understanding and new scientific insights. To ensure that GML receives fair credit for their work please include relevant citation text in publications.”
From the producer's terms, checked 2026-10-04; re-checked automatically every week.
Credit we give: NOAA Global Monitoring Laboratory (Lan, Thoning & Dlugokencky), version {version}, doi:10.15138/P8XG-AA10.
Notice: The NOAA Global Monitoring Laboratory methane and nitrous oxide global marine surface means are US Government material 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: Lan, X., K.W. Thoning, and E.J. Dlugokencky: Trends in globally-averaged CH4, N2O, and SF6 determined from NOAA Global Monitoring Laboratory measurements. Version {version}, https://doi.org/10.15138/P8XG-AA10

Files

Annual mean methane averaged over global marine surface sites, from 1984 (ppb).
https://gml.noaa.gov/webdata/ccgg/trends/ch4/ch4_annmean_gl.csv
Annual mean nitrous oxide averaged over global marine surface sites, from 2001 (ppb).
https://gml.noaa.gov/webdata/ccgg/trends/n2o/n2o_annmean_gl.csv

Status

Programme: Still publishing monthly (version 2026-09, files created 5 September 2026). The FY2026 and FY2027 US budget requests proposed closing NOAA's research labs, including GML; Congress rejected the FY2026 closure.
Updates: Monthly, around the 5th of the month
Next release: 2026-10-05: Version 2026-10 of the monthly and annual files.
Last check: Unchanged since the last fetch (2026-10-05T11:04:24Z)