Greenhouse Gas Levels Reach New Highs As Global Warming Risks Continue Climbing Worldwide Rapidly
Synopsis
Atmospheric pollution linked to climate change has reached another milestone, raising concerns among scientists about intensifying weather extremes and new environmental risks in the years ahead.
Greenhouse gas concentrations in the atmosphere climbed to record levels in 2025, according to new findings from the World Meteorological Organization (WMO), reinforcing concerns that the planet could face even stronger warming and more severe weather extremes in the coming years.
The report, released ahead of the COP31 climate summit in Antalya, Türkiye, shows that carbon dioxide, methane and nitrous oxide all reached unprecedented concentrations last year. Scientists warn that the continued build-up of heat-trapping gases is adding pressure to the climate system at a time when many regions are already experiencing more intense heatwaves, storms and flooding.
According to the WMO, global average atmospheric carbon dioxide concentrations reached 426.8 parts per million in 2025. That level represents approximately 153 per cent of concentrations recorded before the industrial era and reflects an increase of 2.8 parts per million compared with the previous year.
The annual rise exceeded the average increase recorded during the last decade, highlighting the continued accumulation of greenhouse gases despite ongoing climate mitigation efforts.
Methane and nitrous oxide concentrations also established new records. The WMO reported that atmospheric methane levels reached 267 per cent of pre-industrial concentrations, while nitrous oxide stood at 126 per cent of historical levels.
Unlike annual emissions inventories, the report focuses on the quantities of greenhouse gases that remain in the atmosphere and continue influencing global temperatures.
The findings are expected to feature prominently during climate discussions at COP31, where governments will review progress on emissions reduction commitments and adaptation strategies.
WMO Deputy Secretary-General Ko Barrett warned that every additional increase in greenhouse gas concentrations contributes further to planetary warming by trapping more heat within the atmosphere and oceans.
According to the agency, the consequences are already becoming increasingly visible through worsening weather-related disasters across multiple continents.
During 2026, several regions experienced unusually high temperatures, while parts of Asia and other areas endured destructive flood events.
El Niño Could Intensify Atmospheric Build-Up Further
Scientists are also concerned about the potential influence of a strengthening El Niño event.
The WMO expects greenhouse gas concentrations to continue increasing in 2026 due to ongoing fossil fuel use and changing climate conditions associated with El Niño. Drier conditions linked to the phenomenon may reduce the ability of forests, soils and other natural carbon sinks to absorb emissions from the atmosphere.
Beyond carbon dioxide, the agency highlighted growing concern about sulfur hexafluoride, known as SF6.
Widely used in electrical equipment, SF6 recorded its largest increase on record during 2025. The gas has a global warming effect more than 24,000 times stronger than carbon dioxide and can remain in the atmosphere for over a thousand years.
The report also examined rising hydrogen concentrations.
Although hydrogen itself is not classified as a greenhouse gas, leaks from infrastructure involved in producing, transporting and storing hydrogen can alter atmospheric chemistry and indirectly contribute to warming. Global hydrogen concentrations increased by 5.3 per cent between 2010 and 2024, according to the findings.
The WMO cautioned that unmanaged hydrogen leakage and the long atmospheric lifespan of SF6 could weaken some of the climate benefits associated with the global transition toward cleaner energy systems.
At the same time, the organisation stressed that the energy transition remains essential for reducing long-term climate risks.