Daily CO2

Mauna Loa Observatory  |  Atmospheric CO2 Concentrations

March 23, 2017

406.66 ppm

March 23, 2016

405.32 ppm


daily mean concentrations  |  ppm = parts per million

Highest-ever daily average CO2 at MLO:  409.44 ppm on April 9, 2016 (Scripps)
2nd highest daily average CO2 at MLO:  409.39 ppm on April 8, 2016 (Scripps)

Highest daily peak CO2 reported for MLO in 2015:  404.84 ppm on April 13, 2015 (Scripps)


When available, daily average values for carbon dioxide in the atmosphere are posted here as a year-over-year comparison.  Measurements are made by two independent CO2 monitoring programs (NOAA and Scripps) at the Mauna Loa Observatory in Hawaii, about 3400 metres above sea level.

CO2.Earth presents a year-over-year comparison of recent daily readings for public education purposes.  Tracking these readings can provide opportunities for in-the-moment learning about the seasonal cycle and trend for atmospheric CO2.  See the "notes" tab on this page for important information about the daily CO2 data reposted here.


Explore the tabs below to view visuals and links associated with the latest CO2 readings from Mauna Loa.


CO2 Past.  CO2 Present.  CO2 Future.