WMO reports record atmospheric concentrations of carbon dioxide, methane and nitrous oxide, warning of long-term global warming and growing climate risks.
Web Desk: Greenhouse gas concentrations in the atmosphere reached record highs in 2025, raising concerns about further global warming and long-lasting climate impacts, according to the United Nations’ World Meteorological Organization (WMO).
In its latest annual Greenhouse Gas Bulletin, released ahead of the COP31 United Nations climate summit, the WMO reported that concentrations of carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) all increased to unprecedented levels during the year.
The agency warned that the growing accumulation of these gases is trapping more heat in the atmosphere, increasing the risk of extreme weather and creating long-term challenges for economies, societies and ecosystems.
Carbon dioxide concentration reaches 426.8 ppm
According to the WMO report, the global average atmospheric concentration of carbon dioxide reached 426.8 parts per million (ppm) in 2025. Methane rose to 1,948 parts per billion (ppb), while nitrous oxide reached 339.1 ppb.
The reported concentrations correspond to 153%, 267% and 126% of their respective pre-industrial levels, measured against conditions before 1750.
Carbon dioxide remains the largest contributor to warming among the three major long-lived greenhouse gases, accounting for approximately 66% of their combined warming effect, according to the report.
The gas can remain in the climate system for decades to centuries, meaning its effects continue long after emissions occur.
WMO warns of long-term climate risks
WMO Deputy Secretary-General Ko Barrett said greenhouse gases were trapping unprecedented amounts of heat in the atmosphere, contributing to conditions that increase the risks associated with extreme weather.
She also highlighted that the past 11 years were the warmest on record, reinforcing concerns about the continuing global warming trend.
The findings underline the importance of reducing greenhouse gas emissions and strengthening climate action, as the effects of accumulated carbon dioxide can persist for generations.
CO₂ growth slows slightly but remains significant
The WMO reported that the global average concentration of carbon dioxide increased by 2.8 ppm between 2024 and 2025. Although this was below the record annual rise of 3.6 ppm recorded between 2023 and 2024, the increase remained substantial.
The agency attributed the comparatively smaller rise partly to the recovery of land-based carbon sinks and reduced carbon emissions from fires following the strong 2023–2024 El Niño event.
Land and oceans absorb a portion of the carbon dioxide released into the atmosphere, helping limit the amount that accumulates. However, continued fossil fuel consumption remains a major driver of rising atmospheric concentrations.
WMO scientific officer Oksana Tarasova warned that further increases could occur in 2026 as fossil fuel burning continues and El Niño-related conditions potentially affect the ability of land ecosystems to absorb carbon.
Methane and nitrous oxide add to the challenge
Methane is responsible for approximately 16% of the warming effect associated with long-lived greenhouse gases, while nitrous oxide is another significant contributor to global warming.
Methane emissions come from both natural and human-related sources. Natural sources include wetlands, while human activities include livestock farming, rice cultivation, landfills and biomass burning.
Nitrous oxide emissions are associated with natural processes as well as human activities, including agricultural practices.
The latest figures show that efforts to address climate change must extend beyond carbon dioxide to include other heat-trapping gases and the activities responsible for their release.
Attention turns to other potent gases
The WMO also highlighted concerns about sulfur hexafluoride (SF₆), a powerful greenhouse gas used in electrical equipment, particularly for insulation and arc suppression in electricity distribution systems.
Its atmospheric concentration has continued to rise over recent decades. The report also pointed to increasing levels of molecular hydrogen (H₂), although the reasons behind that trend remain uncertain.
The agency said these gases deserve greater attention as countries transition towards lower-carbon energy systems and expand electricity infrastructure.
Climate summit faces growing pressure for action
The findings come ahead of the COP31 United Nations climate summit, scheduled to take place in Antalya, Türkiye, from November 9 to 20, 2026.
The latest WMO assessment adds to international concerns about the gap between climate ambitions and the continuing accumulation of greenhouse gases in the atmosphere.
The central challenge remains reducing emissions while improving the protection of communities, infrastructure and ecosystems against the consequences of a warming planet.
