Climate Tracker
CO2 at Mauna Loa
Monthly mean carbon dioxide in dry air measured at Mauna Loa Observatory, Hawaii, in parts per million.
427.6ppm
Latest reading, August 1, 2026 · +23.0 ppm over 10 years
- Source
- NOAA Global Monitoring Laboratory
https://gml.noaa.gov/webdata/ccgg/trends/co2/co2_mm_mlo.csv - Licence and attribution
- US government data, free to use with citation (confirm with the publisher before publishing)
Source: NOAA Global Monitoring Laboratory, Mauna Loa monthly mean CO2. - Citation and notes
Data from March 1958 through April 1974 were obtained by C. David Keeling of the Scripps Institution of Oceanography (scrippsco2.ucsd.edu).
NOAA's current citation text is on its Trends in CO2 page: https://gml.noaa.gov/ccgg/trends/
Missing months are interpolated by NOAA and flagged in the source file.
From December 2022 to July 2023 the values come from a site at the Maunakea Observatories, because the Mauna Loa eruption suspended measurements there.
- Updates
- Monthly, last copied October 9, 2026
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Show the most recent values▾
| Month | ppm |
|---|---|
| 2026-08 | 427.55 |
| 2026-07 | 429.13 |
| 2026-06 | 431.43 |
| 2026-05 | 432.34 |
| 2026-04 | 431.12 |
| 2026-03 | 430.15 |
| 2026-02 | 429.35 |
| 2026-01 | 428.62 |
| 2025-12 | 427.49 |
| 2025-11 | 426.46 |
| 2025-10 | 424.87 |
| 2025-09 | 424.37 |
| 2025-08 | 425.48 |
| 2025-07 | 427.87 |
| 2025-06 | 429.61 |
| 2025-05 | 430.51 |
| 2025-04 | 429.64 |
| 2025-03 | 428.15 |
| 2025-02 | 427.09 |
| 2025-01 | 426.65 |
| 2024-12 | 425.4 |
| 2024-11 | 423.85 |
| 2024-10 | 422.38 |
| 2024-09 | 422.03 |
Values are copied as the publisher released them, with no adjustment. Methodology