Atmospheric CO₂ at Mauna Loa
426.73 ppm on 2026-10-18, +47.398 ppm against 1991-2020. NOAA Global Monitoring Laboratory, refreshed at every deploy.
Atmospheric CO₂ at Mauna Loa
426.73 ppm · 2026-10-18 · +47.398 ppm vs 1991-2020
1974–2026· baseline 1991-2020 · NOAA Global Monitoring Laboratory, weekly mean, Mauna Loa Observatory · data · json · Freely available under NOAA GML's data use policy; cite it · fetched 2026-10-25· Weekly means; the baseline is the 1991–2020 mean for the same week.
Citations: Lan, X., Tans, P. and K.W. Thoning: Trends in globally-averaged CO2 determined from NOAA Global Monitoring Laboratory measurements. https://gml.noaa.gov/ccgg/trends/