(Geneva, Switzerland) - Carbon dioxide, methane and nitrous oxide reached record global atmospheric concentrations in 2025, the World Meteorological Organization reported October 27.

Its latest Greenhouse Gas Bulletin puts the annual global surface average for carbon dioxide at 426.8 parts per million, 53 per cent above the pre-industrial level. Methane reached 1,948 parts per billion and nitrous oxide 339.1 parts per billion.

These measurements describe gases accumulated in the atmosphere, rather than the amount newly emitted during one year.

Carbon dioxide increased by 2.8 parts per million from 2024. WMO says that was below the exceptional previous annual rise but remained a substantial addition; a slower increase still means concentrations are rising.

The bulletin precedes the November 9–20 COP31 climate conference in Antalya, Türkiye.

Sources: WMO release and Bulletin No. 22 summary, October 27.

Editorial illustration of atmospheric monitoring; not an actual WMO station.