10 Largest Annual Increases in Global Atmospheric CO₂, 1959–2025

The largest increase in this NOAA global series is 3.76 ppm in 2024, followed by 2.95 ppm in 2015. These are the ten highest annual increases among 67 complete years, 1959–2025. The 2025 value is 2.06 ppm and does not enter the top ten.

NOAA Global Monitoring Laboratory’s October 9, 2026 data release reports the net annual change in dry-air mole fraction, in ppm, from the beginning to the end of each year. This is concentration growth after additions and removals, not annual emissions, percentage growth, or the atmospheric concentration level. Before 1980, global growth is approximated from Mauna Loa and South Pole measurements with an offset correction; later data use the global marine boundary layer network. These are not Mauna Loa-only values. Last-year estimates can be revised; 2026 is not a full-year observation.

Published one-standard-deviation uncertainties (ppm): 2024: 3.76 ± 0.11; 2015: 2.95 ± 0.07; 1998: 2.84 ± 0.12; 2016: 2.83 ± 0.08; 2023: 2.69 ± 0.13; 1987: 2.66 ± 0.08; 2019: 2.50 ± 0.06; 2005: 2.47 ± 0.08; 2013: 2.45 ± 0.07; 2012: 2.41 ± 0.07. Small gaps may be within uncertainty; ranks compare point estimates.

Sources checked October 28, 2026. Equal values are ties; display order does not break a tie.