Greenhouse gas levels hit new record highs in 2025: UN

Of the three major greenhouse gases, carbon dioxide accounts for about 66% of the warming effect on the climate.(AFP) — Greenhouse gas concentrations in the atmosphere rose to record highs in 2025, locking in climate impacts that will persist for centuries, the United Nations said Tuesday.Levels of the three main greenhouse gases — carbon dioxide, methane and nitrous oxide — all rose to unprecedented levels in 2025, the U.N.’s weather and climate agency said.The World Meteorological Organization said the rise would lead to further long-term increases in global temperatures.The WMO’s 22nd annual Greenhouse Gas Bulletin comes ahead of the COP31 U.N. climate summit in Antalya, Turkey, which runs Nov. 9-20.“Another year, another new record,” said WMO Deputy Secretary-General Ko Barrett.“Greenhouse gases are trapping an unprecedented amount of heat in the atmosphere, providing energy for more extreme weather and associated risks to our economies and societies.“The past 11 years have been the warmest on record and this trend is set to continue. Carbon dioxide (CO2) has a very long lifetime and so will affect the global climate not just for years but for decades and even centuries.”El Niño effectThe bulletin examines greenhouse gas concentrations — the amounts of those gases in the atmosphere — rather than annual emissions as the world burns more coal, oil and gas.In 2025, carbon dioxide concentrations reached 426.8 parts per million; methane, 1,948 parts per billion; and nitrous oxide, 339.1 parts per billion.Those figures represent 153%, 267% and 126%, respectively, of preindustrial levels before 1750.Of the three major greenhouse gases, carbon dioxide accounts for about 66% of the warming effect on the climate.About half of the carbon dioxide emitted each year remains in the atmosphere; the rest is absorbed by the land and oceans.From 2024 to 2025, the global average concentration of carbon dioxide rose by 2.8 parts per million — less than the record increase of 3.6 parts per million from 2023 to 2024.WMO senior scientific officer Oksana Tarasova said this reflected the “recovery of the land carbon sinks and reduced fire carbon emissions in 2025 after the strong 2023/2024 El Niño,” the naturally occurring, climate-warming weather phenomenon.“However, a 2.8 ppm annual increase is still a substantial addition of carbon to the atmosphere from fossil fuel burning.”It is also above the average annual growth over the past decade of 2.6 parts per million — a figure that stood at 0.8 parts per million in the 1960s.Monitoring station data show that carbon dioxide levels have continued rising in 2026.“Every additional part per million matters because it traps additional heat,” Barrett told reporters.“In effect, we are supercharging the ocean and the atmosphere. That means that heat waves, tropical cyclones, and rainstorms are intensifying faster than our historical baselines prepared us for.”Growing concerns over hydrogen, sulfur hexafluorideMethane accounts for about 16% of the warming effect on the climate from long-lived greenhouse gases, though it has a much shorter lifetime than carbon dioxide.About a third of methane emitted into the atmosphere comes from natural sources such as wetlands, with the rest from human activities such as raising cattle, growing rice, operating landfills and burning biomass.The bulletin said that as countries shift their energy systems toward decarbonization, more attention should be paid to two potent but less abundant trace gases closely related to electricity production and distribution: molecular hydrogen and sulfur hexafluoride.Used primarily as a spark suppressant in electricity distribution, sulfur hexafluoride has been rising steadily in the atmosphere over the past three decades.“Why should we be concerned? Because SF6 has an atmospheric lifetime of up to 3,200 years. Its global warming potential is more than 24,000 times that of CO2,” Barrett told reporters.Why hydrogen levels have increased over the past decade is unknown, but the gas has begun to be used as an energy storage medium.Subscribe to our free newslettersOur weekly newsletter Closing Arguments offers the latest about ongoing trials, major litigation and rulings in courthouses around the U.S. and the world, while the monthly Under the Lights dishes the legal dirt from Hollywood, sports, Big Tech and the arts.Additional Reads