Atmospheric CO₂ — Mauna Loa Annual Means

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NOAA Global Monitoring Laboratory1959–2025ppm (micromol per mol, dry air)

Annual mean atmospheric carbon dioxide concentration measured at Mauna Loa Observatory, Hawaii — the longest continuous record of atmospheric CO₂, begun by C.D. Keeling in 1958.

427.35 ppm (2025)
Latest annual mean
315.98 ppm (1959)
First annual mean
+111.37 ppm
Net change
67
Years of record

ppm over time

315.98343.82371.67399.51427.3519592025

Data

YearCO₂ (ppm)Uncertainty (ppm)
1,959315.980.12
1,960316.910.12
1,961317.640.12
1,962318.450.12
1,963318.990.12
1,964319.620.12
1,965320.040.12
1,966321.370.12
1,967322.180.12
1,968323.050.12
1,969324.620.12
1,970325.680.12
1,971326.320.12
1,972327.460.12
1,973329.680.12
1,974330.190.12
1,975331.130.12
1,976332.030.12
1,977333.840.12
1,978335.410.12
1,979336.840.12
1,980338.760.12
1,981340.120.12
1,982341.480.12
1,983343.150.12
1,984344.870.12
1,985346.350.12
1,986347.610.12
1,987349.310.12
1,988351.690.12
1,989353.20.12
1,990354.450.12
1,991355.70.12
1,992356.540.12
1,993357.210.12
1,994358.960.12
1,995360.970.12
1,996362.740.12
1,997363.880.12
1,998366.840.12
1,999368.540.12
2,000369.710.12
2,001371.320.12
2,002373.450.12
2,003375.980.12
2,004377.70.12
2,005379.980.12
2,006382.090.12
2,007384.020.12
2,008385.830.12
2,009387.640.12
2,010390.10.12
2,011391.850.12
2,012394.060.12
2,013396.740.12
2,014398.810.12
2,015401.010.12
2,016404.410.12
2,017406.760.12
2,018408.720.12
2,019411.650.12
2,020414.210.12
2,021416.410.12
2,022418.530.12
2,023421.080.12
2,024424.610.12
2,025427.350.12

Provenance

Original Source
Keeling Curve, Mauna Loa Observatory — NOAA Global Monitoring Laboratory
Direct Data URL
https://gml.noaa.gov/webdata/ccgg/trends/co2/co2_annmean_mlo.csv
License
Public domain (U.S. Government work, 17 U.S.C. § 105)
Retrieved
Thu, 02 Jul 2026 01:01:07 GMT