NOAA Global Monitoring Laboratory
Trends in atmospheric carbon dioxide
Monthly and annual mean concentrations measured at Mauna Loa Observatory, Hawaii, and averaged over NOAA's global network of marine surface sites. The Mauna Loa record before May 1974 was measured by C. David Keeling of the Scripps Institution of Oceanography.
Free to reuse with creditAt riskUS federal programmeFetched automatically
Numbers published from it
Licence and credit
- 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, Tans & Thoning), version {version}, doi:10.15138/9N0H-ZH07. Mauna Loa data March 1958 to April 1974: C. David Keeling, Scripps Institution of Oceanography.
- Notice
- The NOAA Global Monitoring Laboratory greenhouse gas trend values (Mauna Loa carbon dioxide from May 1974, and the 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., Tans, P. and K.W. Thoning: Trends in globally-averaged CO2 determined from NOAA Global Monitoring Laboratory measurements. Version {version} https://doi.org/10.15138/9N0H-ZH07
Files
Monthly mean CO2 at Mauna Loa, from March 1958 (ppm).
https://gml.noaa.gov/webdata/ccgg/trends/co2/co2_mm_mlo.csvAnnual mean CO2 at Mauna Loa, from 1959 (ppm).
https://gml.noaa.gov/webdata/ccgg/trends/co2/co2_annmean_mlo.csvAnnual mean CO2 averaged over global marine surface sites, from 1979 (ppm).
https://gml.noaa.gov/webdata/ccgg/trends/co2/co2_annmean_gl.csvMonthly mean CO2 averaged over global marine surface sites, from 1979 (ppm).
https://gml.noaa.gov/webdata/ccgg/trends/co2/co2_mm_gl.csvAnnual CO2 increase from January 1 to December 31, global marine surface sites (ppm per year).
https://gml.noaa.gov/webdata/ccgg/trends/co2/co2_gr_gl.csv
Status
- Programme
- Still publishing monthly (the August 2026 value appeared on 5 September 2026). The FY2026 and FY2027 US budget requests proposed closing NOAA's research labs, including GML and Mauna Loa Observatory; Congress rejected the FY2026 closure. Mauna Loa has had no mains power since the 2022 eruption.
- Updates
- Monthly, around the 5th of the month
- Next release
- 2026-10-05: September 2026 monthly values.
- Last check
- Unchanged since the last fetch (2026-10-05T11:04:23Z)
- Independent sources measuring the same thing
- Scripps CO2 Program atmospheric CO2 and carbon-13 records at Mauna Loa