NOTICE (March 2018): This website provides access to the CDIAC archive data temporarily. It will be gradually transitioned into data packages in the new ESS-DIVE archive. This site will continue to operate in parallel during and after the transition, and will be retired at a future date. If you have any questions regarding the data or the transition, please contact

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Atmospheric CO2 Records from Sites in the Main Geophysical Observatory Air Sampling Network

Main Geophysical Observatory monitoring sites

Map showing location of the Main Geophysical Observatory air sampling network sites