Greenhouse gas levels reached record highs in 2025, locking in long-term climate impacts, the United Nations reported. Concentrations of carbon dioxide, methane, and nitrous oxide all rose to unprecedented figures. The World Meteorological Organization indicated this increase would cause further long-term planetary temperature rises. This bulletin focuses on atmospheric gas concentrations instead of annual emissions.In 2025, carbon dioxide concentrations hit 426.8 parts per million, methane reached 1,948 parts per billion, and nitrous oxide was at 339.1 parts per billion. These levels represent significant increases from pre-industrial figures before 1750. Carbon dioxide alone contributes approximately 66% of the overall warming effect.Roughly half of all CO2 emitted annually stays in the atmosphere. From 2024 to 2025, CO2 concentrations globally increased by 2.8 ppm, less than the previous record surge. This smaller increase was attributed to land carbon sink recovery and fewer fire emissions after a strong El Nino. However, this 2.8 ppm increase remains a significant addition of carbon from fossil fuel combustion. It also exceeds the average growth rate for the past decade and the 1960s. These trapped greenhouse gases are fueling extreme weather and posing risks to economies and societies.