World Meteorological Organization reports record greenhouse gas concentrations in its Greenhouse Gas Bulletin

27 October 2026

The World Meteorological Organization said in its Greenhouse Gas Bulletin that concentrations of carbon dioxide and other major greenhouse gases in the atmosphere reached record highs in 2025, with the average global concentration of carbon dioxide at 153 per cent of the 1750 pre-industrial baseline. Methane and nitrous oxide, the second and third most important long-lived greenhouse gases caused by human activities, also hit new peaks. When the Bulletin was first published in 2004, the annual average carbon dioxide level measured by the organization's Global Atmosphere Watch network was 377.5 parts per million, against nearly 427 parts per million today. Deputy Secretary-General Ko Barrett said the past 11 years have been the warmest on record. The Bulletin provides data for negotiators ahead of the climate conference at Antalya in Turkiye from 9 to 20 November.