Mauna Loa CO2

March 2021




March 2021
417.64 ppm 417.14 ppm
March 2020 414.74 ppm 414.44 ppm
March 2019 412.18 ppm 411.93 ppm
Last Update: April 7, 2021 April 5, 2021
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.