The World Meteorological Organization (WMO) published its annual Greenhouse Gas Bulletin on Oct. 27. The report states that global average surface CO2 reached 426.8 parts per million (ppm) in 2025, about 153% of the WMO’s 1750 baseline and 2.8 ppm above 2024 levels. Methane and nitrous oxide also reached record levels. The WMO expects concentrations to keep rising in 2026. In its press release highlighting the report, the WMO noted the report is intended to provide authoritative scientific information for negotiators at COP31, which will take place in Antalya, Türkiye, Nov. 9-20.
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