Key facts
- CO2 levels in 2025 were 426.8 parts per million, 153% of pre-industrial levels.
- The past 11 years have been the warmest on record.
- The COP 31 meeting in Antalya, Türkiye, is seeking to turn climate commitments into concrete actions.
Greenhouse gas concentrations in the atmosphere rose to record highs in 2025, locking in climate impact that will persist for centuries, the United Nations' World Meteorological Organization (WMO) said on Tuesday. Levels of carbon dioxide, methane, and nitrous oxide all reached unprecedented figures. The WMO reported that the globally averaged surface concentration of CO2 in 2025 was 426.8 parts per million, or 153% of the 1750 pre-industrial baseline. Concentrations of methane and nitrous oxide also hit new records. The WMO releases the Bulletin annually to provide scientific information for negotiators at UN Climate conferences, with COP 31 scheduled for November 9-20, 2026, in Antalya, Türkiye.