Born in 2021: CO2 then and now

In 2021 the air held 416.41 parts per million of CO₂, the annual mean measured at Mauna Loa.

In 2025, the latest complete year, the annual mean at Mauna Loa was 427.35 ppm: 3% more CO₂ in the air. Figures from the data files retrieved 16 October 2026.

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<a href="https://co2stats.com/co2/born-in/2021"><img src="https://co2stats.com/graphics/born-in-2021.svg" width="1200" height="630" alt="Born in 2021: 416 ppm of CO2 then (annual mean), 427 ppm in 2025 (annual mean), 3% more." style="max-width:100%;height:auto"></a>
<p>Graphic: <a href="https://co2stats.com/co2/born-in/2021">CO2Stats</a>, <a href="https://creativecommons.org/licenses/by/4.0/">CC BY 4.0</a>. Source: Dr. Xin Lan, NOAA/GML (gml.noaa.gov/ccgg/trends/) and Dr. Ralph Keeling, Scripps Institution of Oceanography (scrippsco2.ucsd.edu/). Data used under their sources' terms; no endorsement implied.</p>

Sources and licences

Annual mean CO2, Mauna Loa Observatory, Hawaii. Dr. Xin Lan, NOAA/GML (gml.noaa.gov/ccgg/trends/) and Dr. Ralph Keeling, Scripps Institution of Oceanography (scrippsco2.ucsd.edu/). Retrieved 16 October 2026. Made freely available to the public by NOAA GML, which asks users to give it fair credit with relevant citation text ("USE OF NOAA GML DATA" in the file header). No endorsement by NOAA is implied. Terms, full data file.

The card is licensed CC BY 4.0: share it with a credit and a link. The data keep their sources' terms, and no endorsement is implied.

Another year · CO₂ in the air today