Atmospheric CO₂ at Mauna Loa

427.28 ppm on 2026-10-25, +47.683 ppm against 1991-2020. NOAA Global Monitoring Laboratory, refreshed at every deploy.

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Atmospheric CO₂ at Mauna Loa

427.28 ppm · 2026-10-25 · +47.683 ppm vs 1991-2020

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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 2026-11-05· 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/

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