Mauna Loa CO2

May 2021




May 2021
419.13 ppm TBD
May 2020 417.31 ppm TBD
May 2019 414.86 ppm TBD
Last Update: June 7, 2021 TBD
View Data: NOAA

Mauna Loa Observatory (MLO)  |  Atmospheric CO2
monthly mean concentrations  |  ppm = parts per million

Two independent records of CO2 changes are maintained in parallel at Mauna Loa.   A graph showing the two records together is available at the bottom of the Scripps CO2 Program website.  All-time monthly record highs for CO2 are recorded at the CO2 Records webpage. 

Use the tabs below to view the latest monthly CO2 data, charts and related links.


CO2 Past.  CO2 Present.  CO2 Future.