The amount of carbon dioxide, methane and nitrous oxide in the atmosphere reached record levels in 2025, the World Meteorological Organization said Tuesday. The gases trap heat and contribute to the long-term warming of the climate, the agency said.
The global average carbon dioxide concentration reached 426.8 parts per million, or 53% above the estimated level before industrialization began around 1750. Put another way, the average was about 427 carbon dioxide molecules for every million molecules of dry air. The figure is a global average, not a reading for Adams County.
Methane averaged 1,948 parts per billion, 167% above its preindustrial level. Nitrous oxide averaged 339.1 parts per billion, 26% above its preindustrial level. Both reached new highs, along with carbon dioxide.
Carbon dioxide rose by 2.8 parts per million from 2024 to 2025, Reuters reported. The increase was smaller than the unusually large jump the previous year but remained above the average annual rise over the past decade, the WMO said. Methane’s annual increase eased from 2024.
The measurements track how much gas accumulates in the atmosphere, not emissions in a single year. About half of the carbon dioxide emitted annually remains in the air; land ecosystems and oceans absorb the rest, the WMO said. Carbon dioxide can affect the climate for decades or centuries.
“The past 11 years have been the warmest on record,” said Ko Barrett, the WMO’s deputy secretary-general. The organization says the buildup of heat-trapping gases raises risks from extreme weather.
The bulletin draws on measurements from the WMO’s Global Atmosphere Watch network, which uses observations from 179 stations around the world. The figures represent a long-term global trend rather than conditions at any one location.
The WMO expects concentrations to rise further in 2026 as fossil fuel emissions continue and an expected El Niño affects how much carbon land and oceans absorb. The bulletin was released ahead of the U.N. climate conference, COP31, scheduled for Nov. 9-20 in Antalya, Türkiye.