WMO says greenhouse gases reached new records in 2025

Global atmospheric concentrations of the three main long-lived greenhouse gases reached record highs in 2025, the World Meteorological Organization said on Tuesday. Its Global Atmosphere Watch network measured carbon dioxide at 426.8 parts per million, methane at 1,948 parts per billion and nitrous oxide at 339.1 parts per billion. Those levels were respectively 53%, 167% and 26% above pre-industrial concentrations.

The increase in carbon dioxide from 2024 to 2025 was smaller than the exceptional rise a year earlier but remained slightly above the average annual growth rate of the past decade. Methane’s annual increase slowed below its recent decade average, while nitrous oxide rose by about the same amount as in the preceding year. A slower yearly increment is not a decline in concentration: the total stock in the atmosphere still increased.

WMO’s bulletin is based on globally averaged surface observations from a coordinated monitoring network, not on a single station or a model projection. Reuters reported that the agency expects concentrations to keep rising in 2026. The figures sharpen the baseline before the COP31 climate conference in Antalya in November, where the central question is whether national emissions policies can bend those long-term measurements downward.