Global average carbon dioxide reached 426.8 parts per million in 2025, a new record, according to the World Meteorological Organization Greenhouse Gas Bulletin, as reported by RNZ. The WMO said that level is 153 percent of the 1750 pre-industrial baseline. Methane and nitrous oxide, the next major long-lived greenhouse gases tied to human activity, also rose to records, the bulletin said.

WMO Deputy Secretary-General Ko Barrett said another year brought another record and that greenhouse gases are trapping an unprecedented amount of heat. She said the past 11 years have been the warmest on record and that CO2 will affect climate for decades and even centuries. From 2024 to 2025, the global average CO2 rise was 2.8 ppm, above the recent decade average but below the 2023-2024 surge, WMO said. Scientists linked the slightly slower step to land carbon sinks recovering after a strong El Nino and to fewer fire emissions.

RNZ reported the same 426.8 ppm figure and noted New Zealand's Baring Head station also set local records. An RNZ correction clarified the rise versus 1750 as a 53 percent increase, matching WMO's framing that today's level is 153 percent of the baseline. Methane averaged 1,948 parts per billion and nitrous oxide 339.1 parts per billion in 2025, WMO said. When the bulletin first appeared in 2004, average CO2 was 377.5 ppm. Growth rates have roughly tripled since the 1960s, WMO said. The bulletin feeds talks ahead of COP 31 in Antalya, Turkiye, from November 9 to 20.

What we know: WMO says 2025 CO2 averaged 426.8 ppm, with methane and nitrous oxide also at records.
What we don't: Only RNZ has reported this WMO bulletin so far. NewsHabit hasn't seen independent confirmation.