Daily CO2 readings are updated here automatically with the latest atmospheric CO2 readings available from the Mauna Loa Observatory in Hawaii.
Data sources:
March 1958 to April 1974: Scripps Institution of Oceanography, May 1974 to present day: Dr. Pieter Tans, NOAA/GML
Last update: 4:05:18 AM on Aug. 19, 2026, Hawaii local time (UTC -10)
| Latest | One year ago | Change from previous year | ||
|---|---|---|---|---|
| Date | Reading | Date | Reading | |
| Aug. 18, 2026 | Unavailable | Aug. 18, 2025 | 425.51 ppm | n/a |
| Aug. 17, 2026 | Unavailable | Aug. 17, 2025 | 425.45 ppm | n/a |
| Aug. 16, 2026 | Unavailable | Aug. 16, 2025 | 425.22 ppm | n/a |
| Aug. 15, 2026 | Unavailable | Aug. 15, 2025 | 425.55 ppm | n/a |
| Aug. 14, 2026 | 427.80 ppm | Aug. 14, 2025 | 425.44 ppm | 2.36 ppm increase (0.55 %) |
| Aug. 13, 2026 | 426.95 ppm | Aug. 13, 2025 | 425.50 ppm | 1.45 ppm increase (0.34 %) |
| Aug. 12, 2026 | 428.02 ppm | Aug. 12, 2025 | 425.49 ppm | 2.53 ppm increase (0.59 %) |
| Aug. 11, 2026 | Unavailable | Aug. 11, 2025 | Unavailable | n/a |
| Aug. 10, 2026 | Unavailable | Aug. 10, 2025 | Unavailable | n/a |
| Aug. 9, 2026 | Unavailable | Aug. 9, 2025 | 425.65 ppm | n/a |