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: 2:35:03 AM on Jul. 16, 2025, Hawaii local time (UTC -10)
| Latest | One year ago | Change from previous year | ||
|---|---|---|---|---|
| Date | Reading | Date | Reading | |
| Jul. 15, 2025 | Unavailable | Jul. 15, 2024 | 426.46 ppm | n/a |
| Jul. 14, 2025 | Unavailable | Jul. 14, 2024 | 426.55 ppm | n/a |
| Jul. 13, 2025 | Unavailable | Jul. 13, 2024 | 427.37 ppm | n/a |
| Jul. 12, 2025 | Unavailable | Jul. 12, 2024 | 425.66 ppm | n/a |
| Jul. 11, 2025 | 428.55 ppm | Jul. 11, 2024 | 426.61 ppm | 1.94 ppm increase (0.45 %) |
| Jul. 10, 2025 | 428.43 ppm | Jul. 10, 2024 | Unavailable | n/a |
| Jul. 9, 2025 | 428.43 ppm | Jul. 9, 2024 | 425.81 ppm | 2.62 ppm increase (0.62 %) |
| Jul. 8, 2025 | 428.49 ppm | Jul. 8, 2024 | 425.76 ppm | 2.73 ppm increase (0.64 %) |
| Jul. 7, 2025 | 428.45 ppm | Jul. 7, 2024 | 425.39 ppm | 3.06 ppm increase (0.72 %) |
| Jul. 6, 2025 | 428.11 ppm | Jul. 6, 2024 | 425.50 ppm | 2.61 ppm increase (0.61 %) |