The key facts

  • CO2 concentration in 2025 reached 426.8 ppm — 153% of the 1750 baseline level
  • Methane and nitrous oxide concentrations also reached record values
  • The last 11 years were the warmest period in the history of observations, the WMO notes

New record for greenhouse gas concentrations

The World Meteorological Organization (WMO), in its new Greenhouse Gas Bulletin, reported that in 2025 the concentration of carbon dioxide and other major greenhouse gases in the atmosphere reached an unprecedented level. According to the bulletin, the global average concentration of CO2 near the Earth's surface was 426.8 parts per million (ppm), or 153% of the baseline pre-industrial level of 1750. Concentrations of methane and nitrous oxide — the second and third most significant long-lived greenhouse gases associated with human activity — also reached new records.

What the WMO says

WMO Deputy Secretary-General Ko Barrett commented: 'Another year — another new record. Greenhouse gases are trapping an unprecedented amount of heat in the atmosphere, leading to more intense extreme weather events and the risks they pose to our economy and society.' According to her, the last 11 years have been the warmest period in the history of observations, and this trend is likely to continue. She emphasized that CO2 remains in the atmosphere for a long time and affects the global climate not for years, but for decades and even centuries, which means further planetary warming over the long term.