Greenhouse gases in the atmosphere have reached an all-time high: the UN warns of consequences lasting for centuries

The concentration of greenhouse gases in the atmosphere has reached an all-time high. The UN warns that the further accumulation of these substances will intensify global warming, and its consequences may be felt for centuries, UNN reports, citing a new bulletin from the World Meteorological Organization (WMO) published on October 27.

According to the organization, in 2025, the concentration of carbon dioxide (CO₂) reached 426.8 parts per million, which is 153% of the pre-industrial level in 1750. Meanwhile, the concentration of methane rose to 1,948 parts per billion, or 267% of the pre-industrial level, while nitrous oxide rose to 339.1 parts per billion, equivalent to 126% of the 1750 level.

Details

"Another year, another record. Greenhouse gases are trapping an unprecedented amount of heat in the atmosphere, creating conditions for more extreme weather events and the associated risks for the economy and society," said WMO Deputy Secretary-General Ko Barrett.

According to her, the past 11 years have been the warmest on record, and this trend is likely to continue. Because carbon dioxide remains in the atmosphere for a long time, its impact on the climate will be felt not only for decades but also for centuries.

The organization also drew attention to the accelerating rate of CO₂ accumulation. Since the 1960s, the average annual rate of increase in its concentration has tripled. While the figure was about 0.8 parts per million per year at that time, it rose to 2.4 in 2011–2020. From 2024 to 2025 alone, the concentration of carbon dioxide increased by another 2.8 parts per million.

WMO senior scientific officer Oksana Tarasova explained that the somewhat slower growth rate compared with the previous year was linked to the recovery of the ability of terrestrial ecosystems to absorb carbon and a reduction in emissions from wildfires following the powerful El Niño climate phenomenon in 2023–2024. She also warned that CO₂ concentrations will continue to rise in 2026 due to the use of fossil fuels and the development of a new powerful El Niño, which could affect natural carbon-absorption mechanisms.

In addition, scientists are concerned about the accumulation of other gases, including sulfur hexafluoride, which is used in the power sector and can remain in the atmosphere for more than a thousand years.

Context

The new WMO report was published ahead of the UN climate conference COP31, which will take place on November 9–20, 2026, in Antalya, Turkey. One of the main issues is expected to be the implementation of international commitments to reduce greenhouse gas emissions and curb global warming.

For reference

Earlier, we wrote that over the next five years, the average temperature on Earth could, for the first time, exceed the 2°C threshold. The reason is the record concentration of carbon dioxide in the atmosphere.