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: 4:05:02 AM on May. 17, 2026, Hawaii local time (UTC -10)
| Latest | One year ago | Change from previous year | ||
|---|---|---|---|---|
| Date | Reading | Date | Reading | |
| May. 16, 2026 | 432.49 ppm | May. 16, 2025 | 430.51 ppm | 1.98 ppm increase (0.46 %) |
| May. 15, 2026 | Unavailable | May. 15, 2025 | 430.55 ppm | n/a |
| May. 14, 2026 | 431.82 ppm | May. 14, 2025 | 430.69 ppm | 1.13 ppm increase (0.26 %) |
| May. 13, 2026 | 432.04 ppm | May. 13, 2025 | Unavailable | n/a |
| May. 12, 2026 | 431.98 ppm | May. 12, 2025 | Unavailable | n/a |
| May. 11, 2026 | 431.95 ppm | May. 11, 2025 | Unavailable | n/a |
| May. 10, 2026 | 433.47 ppm | May. 10, 2025 | 431.25 ppm | 2.22 ppm increase (0.51 %) |
| May. 9, 2026 | Unavailable | May. 9, 2025 | 430.92 ppm | n/a |
| May. 8, 2026 | Unavailable | May. 8, 2025 | 430.81 ppm | n/a |
| May. 7, 2026 | Unavailable | May. 7, 2025 | 430.52 ppm | n/a |