WMO Greenhouse Gas Bulletin - No. 22

The latest analysis of observations from the WMO Global Atmosphere Watch (GAW) in situ observational network shows that the globally averaged surface concentrations(iii) for carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) reached unprecedented highs in 2025, with CO₂ at 426.8±0.2 ppm,(iv) CH₄ at 1 948±2 ppb and N₂O at 339.1±0.1 ppb. These values constitute, respectively, increases of 53%, 167% and 26% above pre-industrial (before 1750) levels. 

The increase in CO₂ from 2024 to 2025 was lower than the anomalously high increase from 2023 to 2024 but slightly higher than the average annual growth rate over the last decade (2016–2025). For CH₄, the increase from 2024 to 2025 was lower than that observed from 2023 to 2024 and also lower than the average annual growth rate over the last decade. For N₂O, the increase from 2024 to 2025 was the same as that observed from 2023 to 2024 and close to the average annual growth rate over the last decade.