Carbon dioxide in the air above Mauna Loa, Hawaii, measured every month since March 1958. The line saws up and down with the Northern Hemisphere seasons, but underneath it only climbs. Data through , released by NOAA Global Monitoring Laboratory.
Monthly CO2 at Mauna Loa
Parts per million (ppm). Hover or touch the chart to read any month.
Monthly meanSeasonally adjusted trend
How fast it is rising
Annual increase in ppm (December to January growth, NOAA). Darker bars are the five fastest years.
The breathing planet
Average gap between each month and the seasonally adjusted trend, . Plants in the north draw CO2 down each summer and release it in winter.
Show the data as a table (annual means and growth)
Year
Annual mean (ppm)
Growth (ppm/yr)
Sources
Lan, X., Tans, P. and Thoning, K.W.: Trends in globally-averaged CO2 determined from NOAA Global Monitoring Laboratory measurements. Monthly mean data, Mauna Loa: co2_mm_mlo.csv (file created Fri Oct 9 13:08:07 2026).
March 1958 to April 1974 data by C. David Keeling, Scripps Institution of Oceanography (scrippsco2.ucsd.edu). After the 2022 Mauna Loa eruption, December 2022 to early July 2023 values come from a site on Maunakea, about 21 miles north.
Some early months are interpolated by NOAA where no measurements exist. All figures on this page are computed directly from the files above.