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: 3:35:03 AM on Jan. 22, 2026, Hawaii local time (UTC -10)
| Latest | One year ago | Change from previous year | ||
|---|---|---|---|---|
| Date | Reading | Date | Reading | |
| Jan. 21, 2026 | Unavailable | Jan. 21, 2025 | 426.34 ppm | n/a |
| Jan. 20, 2026 | 428.60 ppm | Jan. 20, 2025 | 426.74 ppm | 1.86 ppm increase (0.44 %) |
| Jan. 19, 2026 | 428.41 ppm | Jan. 19, 2025 | 428.37 ppm | 0.04 ppm increase (0.01 %) |
| Jan. 18, 2026 | 428.29 ppm | Jan. 18, 2025 | 426.76 ppm | 1.53 ppm increase (0.36 %) |
| Jan. 17, 2026 | 430.51 ppm | Jan. 17, 2025 | 425.93 ppm | 4.58 ppm increase (1.08 %) |
| Jan. 16, 2026 | 429.39 ppm | Jan. 16, 2025 | 427.67 ppm | 1.72 ppm increase (0.40 %) |
| Jan. 15, 2026 | 428.38 ppm | Jan. 15, 2025 | 426.70 ppm | 1.68 ppm increase (0.39 %) |
| Jan. 14, 2026 | 430.67 ppm | Jan. 14, 2025 | 426.24 ppm | 4.43 ppm increase (1.04 %) |
| Jan. 13, 2026 | Unavailable | Jan. 13, 2025 | Unavailable | n/a |
| Jan. 12, 2026 | 427.90 ppm | Jan. 12, 2025 | 427.39 ppm | 0.51 ppm increase (0.12 %) |