Daily CO2

Mauna Loa Observatory  |  Atmospheric CO2 Concentrations

December 15, 2018

409.59 ppm

December 15, 2017

406.79 ppm


daily mean concentrations  |  ppm = parts per million


Daily Records (by year)

Highest-ever daily average CO2  |  Maua Loa Observatory


Highest CO2 levels recorded so far in 2018:  
 412.60 ppm on May 14, 2018 (Scripps)
412.45 ppm on May 14, 2018 (NOAA-ESRL)
412.37 ppm on April 23, 2018 (NOAA-ESRL)


412.63 ppm on April 26, 2017 (NOAA-ESRL)
411.27 ppm on May 15, 2017 (NOAA-ESRL)


409.44 ppm on April 9, 2016 (Scripps)
409.39 ppm on April 8, 2016 (Scripps)


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.