Atmospheric Carbon Dioxide - Mauna Loa

Monthly mean atmospheric carbon dioxide at Mauna Loa Observatory, Hawaii The carbon dioxide data, measured as the mole fraction in dry air, on Mauna Loa constitute the longest record of direct measurements of CO2 in the atmosphere. They were started by C. David Keeling of the Scripps Institution of Oceanography in March of 1958 at a facility of the National Oceanic and Atmospheric Administration (Keeling, 1976). NOAA started its own CO2 measurements in May of 1974, and they have run in parallel with those made by Scripps since then (Thoning, 1989). The black curve represents the seasonally corrected data. Click here for a description of how we make measurements at Mauna Loa.

Data are reported as a dry mole fraction defined as the number of molecules of carbon dioxide divided by the number of molecules of dry air multiplied by one million (ppm). Click for recent trends in carbon dioxide at Mauna Loa, Hawaii and from the global network.

Click here for the Mauna Loa CO2 monthly mean data.

How to reference content from this page
Dr. Pieter Tans, NOAA/ESRL (www.esrl.noaa.gov/gmd/cgg/trends)

Contact
Pieter Tans, NOAA/ESRL, ph. 303 497 6678, Pieter.Tans@noaa.gov

Acknowledgments
Scripps data courtesy of Dr. Ralph Keeling, Scripps Institution of Oceanography, University of California, San Diego.

Further Reading

  • C.D. Keeling, R.B. Bacastow, A.E. Bainbridge, C.A. Ekdahl, P.R. Guenther, and L.S. Waterman, Atmospheric carbon dioxide variations at Mauna Loa Observatory, Hawaii, Tellus, vol. 28, 538-551, 1976.
  • K.W. Thoning, P.P. Tans, and W.D. Komhyr, Atmospheric carbon dioxide at Mauna Loa Observatory 2. Analysis of the NOAA GMCC data, 1974-1985, J. Geophys. Research, vol. 94, 8549-8565, 1989.